“Array” Methods
_.chunk(array, [size=0])
# Ⓢ Ⓣ Ⓝ
Creates an array of elements split into groups the length of size.
If array can’t be split evenly, the final chunk will be the remaining
elements.
Arguments
array (Array): The array to process.[size=0] (number): The length of each chunk.
Returns
(Array): Returns the new array containing chunks.
Example
_.chunk(['a', 'b', 'c', 'd'], 2);
// → [['a', 'b'], ['c', 'd']]
_.chunk(['a', 'b', 'c', 'd'], 3);
// → [['a', 'b', 'c'], ['d']]
_.compact(array)
# Ⓢ Ⓣ Ⓝ
Creates an array with all falsey values removed. The values false, null,
0, "", undefined, and NaN are falsey.
Arguments
array (Array): The array to compact.
Returns
(Array): Returns the new array of filtered values.
Example
_.compact([0, 1, false, 2, '', 3]);
// → [1, 2, 3]
_.concat(array, [values])
# Ⓢ Ⓣ Ⓝ
Creates a new array concatenating array with any additional arrays
and/or values.
Arguments
array (Array): The array to concatenate.[values] (…*): The values to concatenate.
Returns
(Array): Returns the new concatenated array.
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);
console.log(other);
// → [1, 2, 3, [4]]
console.log(array);
// → [1]
_.difference(array, [values])
# Ⓢ Ⓣ Ⓝ
Creates an array of unique array values not included in the other
given arrays using SameValueZero
for equality comparisons. The order of result values is determined by the
order they occur in the first array.
Arguments
array (Array): The array to inspect.[values] (…Array): The values to exclude.
Returns
(Array): Returns the new array of filtered values.
Example
_.difference([3, 2, 1], [4, 2]);
// → [3, 1]
_.differenceBy(array, [values], [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.difference except that it accepts iteratee which
is invoked for each element of array and values to generate the criterion
by which they're compared. Result values are chosen from the first array.
The iteratee is invoked with one argument: (value).
Arguments
array (Array): The array to inspect.[values] (…Array): The values to exclude.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(Array): Returns the new array of filtered values.
Example
_.differenceBy([3.1, 2.2, 1.3], [4.4, 2.5], Math.floor);
// → [3.1, 1.3]
// The `_.property` iteratee shorthand.
_.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x');
// → [{ 'x': 2 }]
_.differenceWith(array, [values], [comparator])
# Ⓢ Ⓣ Ⓝ
This method is like _.difference except that it accepts comparator
which is invoked to compare elements of array to values. Result values
are chosen from the first array. The comparator is invoked with two arguments:
(arrVal, othVal).
Arguments
array (Array): The array to inspect.[values] (…Array): The values to exclude.[comparator] (Function): The comparator invoked per element.
Returns
(Array): Returns the new array of filtered values.
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// → [{ 'x': 2, 'y': 1 }]
_.drop(array, [n=1])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array with n elements dropped from the beginning.
Arguments
array (Array): The array to query.[n=1] (number): The number of elements to drop.
Returns
(Array): Returns the slice of array.
Example
_.drop([1, 2, 3]);
// → [2, 3]
_.drop([1, 2, 3], 2);
// → [3]
_.drop([1, 2, 3], 5);
// → []
_.drop([1, 2, 3], 0);
// → [1, 2, 3]
_.dropRight(array, [n=1])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array with n elements dropped from the end.
Arguments
array (Array): The array to query.[n=1] (number): The number of elements to drop.
Returns
(Array): Returns the slice of array.
Example
_.dropRight([1, 2, 3]);
// → [1, 2]
_.dropRight([1, 2, 3], 2);
// → [1]
_.dropRight([1, 2, 3], 5);
// → []
_.dropRight([1, 2, 3], 0);
// → [1, 2, 3]
_.dropRightWhile(array, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array excluding elements dropped from the end.
Elements are dropped until predicate returns falsey. The predicate is
invoked with three arguments: (value, index, array).
Arguments
array (Array): The array to query.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the slice of array.
Example
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.dropRightWhile(users, function(o) { return !o.active; });
// → objects for ['barney']
// The `_.matches` iteratee shorthand.
_.dropRightWhile(users, { 'user': 'pebbles', 'active': false });
// → objects for ['barney', 'fred']
// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(users, ['active', false]);
// → objects for ['barney']
// The `_.property` iteratee shorthand.
_.dropRightWhile(users, 'active');
// → objects for ['barney', 'fred', 'pebbles']
_.dropWhile(array, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array excluding elements dropped from the beginning.
Elements are dropped until predicate returns falsey. The predicate is
invoked with three arguments: (value, index, array).
Arguments
array (Array): The array to query.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the slice of array.
Example
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': true }
];
_.dropWhile(users, function(o) { return !o.active; });
// → objects for ['pebbles']
// The `_.matches` iteratee shorthand.
_.dropWhile(users, { 'user': 'barney', 'active': false });
// → objects for ['fred', 'pebbles']
// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(users, ['active', false]);
// → objects for ['pebbles']
// The `_.property` iteratee shorthand.
_.dropWhile(users, 'active');
// → objects for ['barney', 'fred', 'pebbles']
_.fill(array, value, [start=0], [end=array.length])
# Ⓢ Ⓣ Ⓝ
Fills elements of array with value from start up to, but not
including, end.
Note: This method mutates array.
Arguments
array (Array): The array to fill.value (*): The value to fill array with.[start=0] (number): The start position.[end=array.length] (number): The end position.
Returns
(Array): Returns array.
Example
var array = [1, 2, 3];
_.fill(array, 'a');
console.log(array);
// → ['a', 'a', 'a']
_.fill(Array(3), 2);
// → [2, 2, 2]
_.fill([4, 6, 8, 10], '*', 1, 3);
// → [4, '*', '*', 10]
_.findIndex(array, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.find except that it returns the index of the first
element predicate returns truthy for instead of the element itself.
Arguments
array (Array): The array to search.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(number): Returns the index of the found element, else -1.
Example
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': true }
];
_.findIndex(users, function(o) { return o.user == 'barney'; });
// → 0
// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// → 1
// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// → 0
// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// → 2
_.findLastIndex(array, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.findIndex except that it iterates over elements
of collection from right to left.
Arguments
array (Array): The array to search.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(number): Returns the index of the found element, else -1.
Example
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.findLastIndex(users, function(o) { return o.user == 'pebbles'; });
// → 2
// The `_.matches` iteratee shorthand.
_.findLastIndex(users, { 'user': 'barney', 'active': true });
// → 0
// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(users, ['active', false]);
// → 2
// The `_.property` iteratee shorthand.
_.findLastIndex(users, 'active');
// → 0
_.flatten(array)
# Ⓢ Ⓣ Ⓝ
Flattens array a single level deep.
Arguments
array (Array): The array to flatten.
Returns
(Array): Returns the new flattened array.
Example
_.flatten([1, [2, [3, [4]], 5]]);
// → [1, 2, [3, [4]], 5]
_.flattenDeep(array)
# Ⓢ Ⓣ Ⓝ
Recursively flattens array.
Arguments
array (Array): The array to flatten.
Returns
(Array): Returns the new flattened array.
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// → [1, 2, 3, 4, 5]
_.flattenDepth(array, [depth=1])
# Ⓢ Ⓣ Ⓝ
Recursively flatten array up to depth times.
Arguments
array (Array): The array to flatten.[depth=1] (number): The maximum recursion depth.
Returns
(Array): Returns the new flattened array.
Example
var array = [1, [2, [3, [4]], 5]];
_.flattenDepth(array, 1);
// → [1, 2, [3, [4]], 5]
_.flattenDepth(array, 2);
// → [1, 2, 3, [4], 5]
_.fromPairs(pairs)
# Ⓢ Ⓣ Ⓝ
The inverse of _.toPairs; this method returns an object composed
from key-value pairs.
Arguments
pairs (Array): The key-value pairs.
Returns
(Object): Returns the new object.
Example
_.fromPairs([['fred', 30], ['barney', 40]]);
// → { 'fred': 30, 'barney': 40 }
_.head(array)
# Ⓢ Ⓣ Ⓝ
Gets the first element of array.
Aliases
_.first
Arguments
array (Array): The array to query.
Returns
(*): Returns the first element of array.
Example
_.head([1, 2, 3]);
// → 1
_.head([]);
// → undefined
_.indexOf(array, value, [fromIndex=0])
# Ⓢ Ⓣ Ⓝ
Gets the index at which the first occurrence of value is found in array
using SameValueZero
for equality comparisons. If fromIndex is negative, it’s used as the offset
from the end of array.
Arguments
array (Array): The array to search.value (*): The value to search for.[fromIndex=0] (number): The index to search from.
Returns
(number): Returns the index of the matched value, else -1.
Example
_.indexOf([1, 2, 1, 2], 2);
// → 1
// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// → 3
_.initial(array)
# Ⓢ Ⓣ Ⓝ
Gets all but the last element of array.
Arguments
array (Array): The array to query.
Returns
(Array): Returns the slice of array.
Example
_.initial([1, 2, 3]);
// → [1, 2]
_.intersection([arrays])
# Ⓢ Ⓣ Ⓝ
Creates an array of unique values that are included in all given arrays
using SameValueZero
for equality comparisons. The order of result values is determined by the
order they occur in the first array.
Arguments
[arrays] (…Array): The arrays to inspect.
Returns
(Array): Returns the new array of intersecting values.
Example
_.intersection([2, 1], [4, 2], [1, 2]);
// → [2]
_.intersectionBy([arrays], [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.intersection except that it accepts iteratee
which is invoked for each element of each arrays to generate the criterion
by which they're compared. Result values are chosen from the first array.
The iteratee is invoked with one argument: (value).
Arguments
[arrays] (…Array): The arrays to inspect.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(Array): Returns the new array of intersecting values.
Example
_.intersectionBy([2.1, 1.2], [4.3, 2.4], Math.floor);
// → [2.1]
// The `_.property` iteratee shorthand.
_.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// → [{ 'x': 1 }]
_.intersectionWith([arrays], [comparator])
# Ⓢ Ⓣ Ⓝ
This method is like _.intersection except that it accepts comparator
which is invoked to compare elements of arrays. Result values are chosen
from the first array. The comparator is invoked with two arguments:
(arrVal, othVal).
Arguments
[arrays] (…Array): The arrays to inspect.[comparator] (Function): The comparator invoked per element.
Returns
(Array): Returns the new array of intersecting values.
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.intersectionWith(objects, others, _.isEqual);
// → [{ 'x': 1, 'y': 2 }]
_.join(array, [separator=','])
# Ⓢ Ⓣ Ⓝ
Converts all elements in array into a string separated by separator.
Arguments
array (Array): The array to convert.[separator=','] (string): The element separator.
Returns
(string): Returns the joined string.
Example
_.join(['a', 'b', 'c'], '~');
// → 'a~b~c'
_.last(array)
# Ⓢ Ⓣ Ⓝ
Gets the last element of array.
Arguments
array (Array): The array to query.
Returns
(*): Returns the last element of array.
Example
_.last([1, 2, 3]);
// → 3
_.lastIndexOf(array, value, [fromIndex=array.length-1])
# Ⓢ Ⓣ Ⓝ
This method is like _.indexOf except that it iterates over elements of
array from right to left.
Arguments
array (Array): The array to search.value (*): The value to search for.[fromIndex=array.length-1] (number): The index to search from.
Returns
(number): Returns the index of the matched value, else -1.
Example
_.lastIndexOf([1, 2, 1, 2], 2);
// → 3
// Search from the `fromIndex`.
_.lastIndexOf([1, 2, 1, 2], 2, 2);
// → 1
_.pull(array, [values])
# Ⓢ Ⓣ Ⓝ
Removes all given values from array using
SameValueZero
for equality comparisons.
Note: Unlike _.without, this method mutates array. Use _.remove
to remove elements from an array by predicate.
Arguments
array (Array): The array to modify.[values] (…*): The values to remove.
Returns
(Array): Returns array.
Example
var array = [1, 2, 3, 1, 2, 3];
_.pull(array, 2, 3);
console.log(array);
// → [1, 1]
_.pullAll(array, values)
# Ⓢ Ⓣ Ⓝ
This method is like _.pull except that it accepts an array of values to remove.
Note: Unlike _.difference, this method mutates array.
Arguments
array (Array): The array to modify.values (Array): The values to remove.
Returns
(Array): Returns array.
Example
var array = [1, 2, 3, 1, 2, 3];
_.pullAll(array, [2, 3]);
console.log(array);
// → [1, 1]
_.pullAllBy(array, values, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.pullAll except that it accepts iteratee which is
invoked for each element of array and values to generate the criterion
by which they're compared. The iteratee is invoked with one argument: (value).
Note: Unlike _.differenceBy, this method mutates array.
Arguments
array (Array): The array to modify.values (Array): The values to remove.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(Array): Returns array.
Example
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];
_.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x');
console.log(array);
// → [{ 'x': 2 }]
_.pullAllWith(array, values, [comparator])
# Ⓢ Ⓣ Ⓝ
This method is like _.pullAll except that it accepts comparator which
is invoked to compare elements of array to values. The comparator is
invoked with two arguments: (arrVal, othVal).
Note: Unlike _.differenceWith, this method mutates array.
Arguments
array (Array): The array to modify.values (Array): The values to remove.[comparator] (Function): The comparator invoked per element.
Returns
(Array): Returns array.
Example
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }];
_.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual);
console.log(array);
// → [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]
_.pullAt(array, [indexes])
# Ⓢ Ⓣ Ⓝ
Removes elements from array corresponding to indexes and returns an
array of removed elements.
Note: Unlike _.at, this method mutates array.
Arguments
array (Array): The array to modify.[indexes] (…(number|number[]): The indexes of elements to remove, specified individually or in arrays.
Returns
(Array): Returns the new array of removed elements.
Example
var array = [5, 10, 15, 20];
var evens = _.pullAt(array, 1, 3);
console.log(array);
// → [5, 15]
console.log(evens);
// → [10, 20]
_.remove(array, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Removes all elements from array that predicate returns truthy for
and returns an array of the removed elements. The predicate is invoked
with three arguments: (value, index, array).
Note: Unlike _.filter, this method mutates array. Use _.pull
to pull elements from an array by value.
Arguments
array (Array): The array to modify.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the new array of removed elements.
Example
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
return n % 2 == 0;
});
console.log(array);
// → [1, 3]
console.log(evens);
// → [2, 4]
_.reverse()
# Ⓢ Ⓣ Ⓝ
Reverses array so that the first element becomes the last, the second
element becomes the second to last, and so on.
Note: This method mutates array and is based on
Array#reverse.
Returns
(Array): Returns array.
Example
var array = [1, 2, 3];
_.reverse(array);
// → [3, 2, 1]
console.log(array);
// → [3, 2, 1]
_.slice(array, [start=0], [end=array.length])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array from start up to, but not including, end.
Note: This method is used instead of Array#slice
to ensure dense arrays are returned.
Arguments
array (Array): The array to slice.[start=0] (number): The start position.[end=array.length] (number): The end position.
Returns
(Array): Returns the slice of array.
_.sortedIndex(array, value)
# Ⓢ Ⓣ Ⓝ
Uses a binary search to determine the lowest index at which value should
be inserted into array in order to maintain its sort order.
Arguments
array (Array): The sorted array to inspect.value (*): The value to evaluate.
Returns
(number): Returns the index at which value should be inserted into array.
Example
_.sortedIndex([30, 50], 40);
// → 1
_.sortedIndex([4, 5], 4);
// → 0
_.sortedIndexBy(array, value, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.sortedIndex except that it accepts iteratee
which is invoked for value and each element of array to compute their
sort ranking. The iteratee is invoked with one argument: (value).
Arguments
array (Array): The sorted array to inspect.value (*): The value to evaluate.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(number): Returns the index at which value should be inserted into array.
Example
var dict = { 'thirty': 30, 'forty': 40, 'fifty': 50 };
_.sortedIndexBy(['thirty', 'fifty'], 'forty', _.propertyOf(dict));
// → 1
// The `_.property` iteratee shorthand.
_.sortedIndexBy([{ 'x': 4 }, { 'x': 5 }], { 'x': 4 }, 'x');
// → 0
_.sortedIndexOf(array, value)
# Ⓢ Ⓣ Ⓝ
This method is like _.indexOf except that it performs a binary
search on a sorted array.
Arguments
array (Array): The array to search.value (*): The value to search for.
Returns
(number): Returns the index of the matched value, else -1.
Example
_.sortedIndexOf([1, 1, 2, 2], 2);
// → 2
_.sortedLastIndex(array, value)
# Ⓢ Ⓣ Ⓝ
This method is like _.sortedIndex except that it returns the highest
index at which value should be inserted into array in order to
maintain its sort order.
Arguments
array (Array): The sorted array to inspect.value (*): The value to evaluate.
Returns
(number): Returns the index at which value should be inserted into array.
Example
_.sortedLastIndex([4, 5], 4);
// → 1
_.sortedLastIndexBy(array, value, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.sortedLastIndex except that it accepts iteratee
which is invoked for value and each element of array to compute their
sort ranking. The iteratee is invoked with one argument: (value).
Arguments
array (Array): The sorted array to inspect.value (*): The value to evaluate.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(number): Returns the index at which value should be inserted into array.
Example
// The `_.property` iteratee shorthand.
_.sortedLastIndexBy([{ 'x': 4 }, { 'x': 5 }], { 'x': 4 }, 'x');
// → 1
_.sortedLastIndexOf(array, value)
# Ⓢ Ⓣ Ⓝ
This method is like _.lastIndexOf except that it performs a binary
search on a sorted array.
Arguments
array (Array): The array to search.value (*): The value to search for.
Returns
(number): Returns the index of the matched value, else -1.
Example
_.sortedLastIndexOf([1, 1, 2, 2], 2);
// → 3
_.sortedUniq(array)
# Ⓢ Ⓣ Ⓝ
This method is like _.uniq except that it’s designed and optimized
for sorted arrays.
Arguments
array (Array): The array to inspect.
Returns
(Array): Returns the new duplicate free array.
Example
_.sortedUniq([1, 1, 2]);
// → [1, 2]
_.sortedUniqBy(array, [iteratee])
# Ⓢ Ⓣ Ⓝ
This method is like _.uniqBy except that it’s designed and optimized
for sorted arrays.
Arguments
array (Array): The array to inspect.[iteratee] (Function): The iteratee invoked per element.
Returns
(Array): Returns the new duplicate free array.
Example
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
// → [1.1, 2.3]
_.tail(array)
# Ⓢ Ⓣ Ⓝ
Gets all but the first element of array.
Arguments
array (Array): The array to query.
Returns
(Array): Returns the slice of array.
Example
_.tail([1, 2, 3]);
// → [2, 3]
_.take(array, [n=1])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array with n elements taken from the beginning.
Arguments
array (Array): The array to query.[n=1] (number): The number of elements to take.
Returns
(Array): Returns the slice of array.
Example
_.take([1, 2, 3]);
// → [1]
_.take([1, 2, 3], 2);
// → [1, 2]
_.take([1, 2, 3], 5);
// → [1, 2, 3]
_.take([1, 2, 3], 0);
// → []
_.takeRight(array, [n=1])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array with n elements taken from the end.
Arguments
array (Array): The array to query.[n=1] (number): The number of elements to take.
Returns
(Array): Returns the slice of array.
Example
_.takeRight([1, 2, 3]);
// → [3]
_.takeRight([1, 2, 3], 2);
// → [2, 3]
_.takeRight([1, 2, 3], 5);
// → [1, 2, 3]
_.takeRight([1, 2, 3], 0);
// → []
_.takeRightWhile(array, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array with elements taken from the end. Elements are
taken until predicate returns falsey. The predicate is invoked with three
arguments: (value, index, array).
Arguments
array (Array): The array to query.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the slice of array.
Example
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.takeRightWhile(users, function(o) { return !o.active; });
// → objects for ['fred', 'pebbles']
// The `_.matches` iteratee shorthand.
_.takeRightWhile(users, { 'user': 'pebbles', 'active': false });
// → objects for ['pebbles']
// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(users, ['active', false]);
// → objects for ['fred', 'pebbles']
// The `_.property` iteratee shorthand.
_.takeRightWhile(users, 'active');
// → []
_.takeWhile(array, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates a slice of array with elements taken from the beginning. Elements
are taken until predicate returns falsey. The predicate is invoked with
three arguments: (value, index, array).
Arguments
array (Array): The array to query.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the slice of array.
Example
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false},
{ 'user': 'pebbles', 'active': true }
];
_.takeWhile(users, function(o) { return !o.active; });
// → objects for ['barney', 'fred']
// The `_.matches` iteratee shorthand.
_.takeWhile(users, { 'user': 'barney', 'active': false });
// → objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(users, ['active', false]);
// → objects for ['barney', 'fred']
// The `_.property` iteratee shorthand.
_.takeWhile(users, 'active');
// → []
_.union([arrays])
# Ⓢ Ⓣ Ⓝ
Creates an array of unique values, in order, from all given arrays using
SameValueZero
for equality comparisons.
Arguments
[arrays] (…Array): The arrays to inspect.
Returns
(Array): Returns the new array of combined values.
Example
_.union([2, 1], [4, 2], [1, 2]);
// → [2, 1, 4]
_.unionBy([arrays], [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.union except that it accepts iteratee which is
invoked for each element of each arrays to generate the criterion by which
uniqueness is computed. The iteratee is invoked with one argument: (value).
Arguments
[arrays] (…Array): The arrays to inspect.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(Array): Returns the new array of combined values.
Example
_.unionBy([2.1, 1.2], [4.3, 2.4], Math.floor);
// → [2.1, 1.2, 4.3]
// The `_.property` iteratee shorthand.
_.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// → [{ 'x': 1 }, { 'x': 2 }]
_.unionWith([arrays], [comparator])
# Ⓢ Ⓣ Ⓝ
This method is like _.union except that it accepts comparator which
is invoked to compare elements of arrays. The comparator is invoked
with two arguments: (arrVal, othVal).
Arguments
[arrays] (…Array): The arrays to inspect.[comparator] (Function): The comparator invoked per element.
Returns
(Array): Returns the new array of combined values.
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.unionWith(objects, others, _.isEqual);
// → [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
_.uniq(array)
# Ⓢ Ⓣ Ⓝ
Creates a duplicate-free version of an array, using
SameValueZero
for equality comparisons, in which only the first occurrence of each element
is kept.
Arguments
array (Array): The array to inspect.
Returns
(Array): Returns the new duplicate free array.
Example
_.uniq([2, 1, 2]);
// → [2, 1]
_.uniqBy(array, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.uniq except that it accepts iteratee which is
invoked for each element in array to generate the criterion by which
uniqueness is computed. The iteratee is invoked with one argument: (value).
Arguments
array (Array): The array to inspect.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(Array): Returns the new duplicate free array.
Example
_.uniqBy([2.1, 1.2, 2.3], Math.floor);
// → [2.1, 1.2]
// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// → [{ 'x': 1 }, { 'x': 2 }]
_.uniqWith(array, [comparator])
# Ⓢ Ⓣ Ⓝ
This method is like _.uniq except that it accepts comparator which
is invoked to compare elements of array. The comparator is invoked with
two arguments: (arrVal, othVal).
Arguments
array (Array): The array to inspect.[comparator] (Function): The comparator invoked per element.
Returns
(Array): Returns the new duplicate free array.
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.uniqWith(objects, _.isEqual);
// → [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]
_.unzip(array)
# Ⓢ Ⓣ Ⓝ
This method is like _.zip except that it accepts an array of grouped
elements and creates an array regrouping the elements to their pre-zip
configuration.
Arguments
array (Array): The array of grouped elements to process.
Returns
(Array): Returns the new array of regrouped elements.
Example
var zipped = _.zip(['fred', 'barney'], [30, 40], [true, false]);
// → [['fred', 30, true], ['barney', 40, false]]
_.unzip(zipped);
// → [['fred', 'barney'], [30, 40], [true, false]]
_.unzipWith(array, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.unzip except that it accepts iteratee to specify
how regrouped values should be combined. The iteratee is invoked with the
elements of each group: (…group).
Arguments
array (Array): The array of grouped elements to process.[iteratee=_.identity] (Function): The function to combine regrouped values.
Returns
(Array): Returns the new array of regrouped elements.
Example
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// → [[1, 10, 100], [2, 20, 200]]
_.unzipWith(zipped, _.add);
// → [3, 30, 300]
_.without(array, [values])
# Ⓢ Ⓣ Ⓝ
Creates an array excluding all given values using
SameValueZero
for equality comparisons.
Arguments
array (Array): The array to filter.[values] (…*): The values to exclude.
Returns
(Array): Returns the new array of filtered values.
Example
_.without([1, 2, 1, 3], 1, 2);
// → [3]
_.xor([arrays])
# Ⓢ Ⓣ Ⓝ
Creates an array of unique values that is the symmetric difference
of the given arrays. The order of result values is determined by the order
they occur in the arrays.
Arguments
[arrays] (…Array): The arrays to inspect.
Returns
(Array): Returns the new array of values.
Example
_.xor([2, 1], [4, 2]);
// → [1, 4]
_.xorBy([arrays], [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.xor except that it accepts iteratee which is
invoked for each element of each arrays to generate the criterion by which
by which they're compared. The iteratee is invoked with one argument: (value).
Arguments
[arrays] (…Array): The arrays to inspect.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(Array): Returns the new array of values.
Example
_.xorBy([2.1, 1.2], [4.3, 2.4], Math.floor);
// → [1.2, 4.3]
// The `_.property` iteratee shorthand.
_.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// → [{ 'x': 2 }]
_.xorWith([arrays], [comparator])
# Ⓢ Ⓣ Ⓝ
This method is like _.xor except that it accepts comparator which is
invoked to compare elements of arrays. The comparator is invoked with
two arguments: (arrVal, othVal).
Arguments
[arrays] (…Array): The arrays to inspect.[comparator] (Function): The comparator invoked per element.
Returns
(Array): Returns the new array of values.
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.xorWith(objects, others, _.isEqual);
// → [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
_.zip([arrays])
# Ⓢ Ⓣ Ⓝ
Creates an array of grouped elements, the first of which contains the first
elements of the given arrays, the second of which contains the second elements
of the given arrays, and so on.
Arguments
[arrays] (…Array): The arrays to process.
Returns
(Array): Returns the new array of grouped elements.
Example
_.zip(['fred', 'barney'], [30, 40], [true, false]);
// → [['fred', 30, true], ['barney', 40, false]]
_.zipObject([props=[]], [values=[]])
# Ⓢ Ⓣ Ⓝ
This method is like _.fromPairs except that it accepts two arrays,
one of property names and one of corresponding values.
Arguments
[props=[]] (Array): The property names.[values=[]] (Array): The property values.
Returns
(Object): Returns the new object.
Example
_.zipObject(['a', 'b'], [1, 2]);
// → { 'a': 1, 'b': 2 }
_.zipObjectDeep([props=[]], [values=[]])
# Ⓢ Ⓣ Ⓝ
This method is like _.zipObject except that it supports property paths.
Arguments
[props=[]] (Array): The property names.[values=[]] (Array): The property values.
Returns
(Object): Returns the new object.
Example
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]);
// → { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }
_.zipWith([arrays], [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.zip except that it accepts iteratee to specify
how grouped values should be combined. The iteratee is invoked with the
elements of each group: (…group).
Arguments
[arrays] (…Array): The arrays to process.[iteratee=_.identity] (Function): The function to combine grouped values.
Returns
(Array): Returns the new array of grouped elements.
Example
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
return a + b + c;
});
// → [111, 222]
“Collection” Methods
_.countBy(collection, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates an object composed of keys generated from the results of running
each element of collection through iteratee. The corresponding value
of each key is the number of times the key was returned by iteratee.
The iteratee is invoked with one argument: (value).
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function|Object|string): The iteratee to transform keys.
Returns
(Object): Returns the composed aggregate object.
Example
_.countBy([6.1, 4.2, 6.3], Math.floor);
// → { '4': 1, '6': 2 }
_.countBy(['one', 'two', 'three'], 'length');
// → { '3': 2, '5': 1 }
_.every(collection, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Checks if predicate returns truthy for all elements of collection.
Iteration is stopped once predicate returns falsey. The predicate is
invoked with three arguments: (value, index|key, collection).
Arguments
collection (Array|Object): The collection to iterate over.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(boolean): Returns true if all elements pass the predicate check, else false.
Example
_.every([true, 1, null, 'yes'], Boolean);
// → false
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false }
];
// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// → false
// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// → true
// The `_.property` iteratee shorthand.
_.every(users, 'active');
// → false
_.filter(collection, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Iterates over elements of collection, returning an array of all elements
predicate returns truthy for. The predicate is invoked with three arguments:
(value, index|key, collection).
Arguments
collection (Array|Object): The collection to iterate over.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the new filtered array.
Example
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false }
];
_.filter(users, function(o) { return !o.active; });
// → objects for ['fred']
// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// → objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// → objects for ['fred']
// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// → objects for ['barney']
_.find(collection, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Iterates over elements of collection, returning the first element
predicate returns truthy for. The predicate is invoked with three arguments:
(value, index|key, collection).
Arguments
collection (Array|Object): The collection to search.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(*): Returns the matched element, else undefined.
Example
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
];
_.find(users, function(o) { return o.age < 40; });
// → object for 'barney'
// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// → object for 'pebbles'
// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// → object for 'fred'
// The `_.property` iteratee shorthand.
_.find(users, 'active');
// → object for 'barney'
_.findLast(collection, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.find except that it iterates over elements of
collection from right to left.
Arguments
collection (Array|Object): The collection to search.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(*): Returns the matched element, else undefined.
Example
_.findLast([1, 2, 3, 4], function(n) {
return n % 2 == 1;
});
// → 3
_.flatMap(collection, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates an array of flattened values by running each element in collection
through iteratee and concating its result to the other mapped values.
The iteratee is invoked with three arguments: (value, index|key, collection).
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the new flattened array.
Example
function duplicate(n) {
return [n, n];
}
_.flatMap([1, 2], duplicate);
// → [1, 1, 2, 2]
_.forEach(collection, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Iterates over elements of collection invoking iteratee for each element.
The iteratee is invoked with three arguments: (value, index|key, collection).
Iteratee functions may exit iteration early by explicitly returning false.
Note: As with other "Collections" methods, objects with a "length" property
are iterated like arrays. To avoid this behavior use _.forIn or _.forOwn
for object iteration.
Aliases
_.each
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.
Returns
(Array|Object): Returns collection.
Example
_([1, 2]).forEach(function(value) {
console.log(value);
});
// → logs `1` then `2`
_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
console.log(key);
});
// → logs 'a' then 'b' (iteration order is not guaranteed)
_.forEachRight(collection, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.forEach except that it iterates over elements of
collection from right to left.
Aliases
_.eachRight
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.
Returns
(Array|Object): Returns collection.
Example
_.forEachRight([1, 2], function(value) {
console.log(value);
});
// → logs `2` then `1`
_.groupBy(collection, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates an object composed of keys generated from the results of running
each element of collection through iteratee. The corresponding value
of each key is an array of elements responsible for generating the key.
The iteratee is invoked with one argument: (value).
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function|Object|string): The iteratee to transform keys.
Returns
(Object): Returns the composed aggregate object.
Example
_.groupBy([6.1, 4.2, 6.3], Math.floor);
// → { '4': [4.2], '6': [6.1, 6.3] }
// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// → { '3': ['one', 'two'], '5': ['three'] }
_.includes(collection, value, [fromIndex=0])
# Ⓢ Ⓣ Ⓝ
Checks if value is in collection. If collection is a string it’s checked
for a substring of value, otherwise SameValueZero
is used for equality comparisons. If fromIndex is negative, it’s used as
the offset from the end of collection.
Arguments
collection (Array|Object|string): The collection to search.value (*): The value to search for.[fromIndex=0] (number): The index to search from.
Returns
(boolean): Returns true if value is found, else false.
Example
_.includes([1, 2, 3], 1);
// → true
_.includes([1, 2, 3], 1, 2);
// → false
_.includes({ 'user': 'fred', 'age': 40 }, 'fred');
// → true
_.includes('pebbles', 'eb');
// → true
_.invokeMap(collection, path, [args])
# Ⓢ Ⓣ Ⓝ
Invokes the method at path of each element in collection, returning
an array of the results of each invoked method. Any additional arguments
are provided to each invoked method. If methodName is a function it’s
invoked for, and this bound to, each element in collection.
Arguments
collection (Array|Object): The collection to iterate over.path (Array|Function|string): The path of the method to invoke or the function invoked per iteration.[args] (…*): The arguments to invoke each method with.
Returns
(Array): Returns the array of results.
Example
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort');
// → [[1, 5, 7], [1, 2, 3]]
_.invokeMap([123, 456], String.prototype.split, '');
// → [['1', '2', '3'], ['4', '5', '6']]
_.keyBy(collection, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates an object composed of keys generated from the results of running
each element of collection through iteratee. The corresponding value
of each key is the last element responsible for generating the key. The
iteratee is invoked with one argument: (value).
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function|Object|string): The iteratee to transform keys.
Returns
(Object): Returns the composed aggregate object.
Example
var array = [
{ 'dir': 'left', 'code': 97 },
{ 'dir': 'right', 'code': 100 }
];
_.keyBy(array, function(o) {
return String.fromCharCode(o.code);
});
// → { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }
_.keyBy(array, 'dir');
// → { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }
_.map(collection, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates an array of values by running each element in collection through
iteratee. The iteratee is invoked with three arguments:
(value, index|key, collection).
Many lodash methods are guarded to work as iteratees for methods like
_.every, _.filter, _.map, _.mapValues, _.reject, and _.some.
The guarded methods are:
ary, curry, curryRight, drop, dropRight, every, fill,
invert, parseInt, random, range, rangeRight, slice, some,
sortBy, take, takeRight, template, trim, trimEnd, trimStart,
and words
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the new mapped array.
Example
function square(n) {
return n * n;
}
_.map([4, 8], square);
// → [16, 64]
_.map({ 'a': 4, 'b': 8 }, square);
// → [16, 64] (iteration order is not guaranteed)
var users = [
{ 'user': 'barney' },
{ 'user': 'fred' }
];
// The `_.property` iteratee shorthand.
_.map(users, 'user');
// → ['barney', 'fred']
_.orderBy(collection, [iteratees=[_.identity]], [orders])
# Ⓢ Ⓣ Ⓝ
This method is like _.sortBy except that it allows specifying the sort
orders of the iteratees to sort by. If orders is unspecified, all values
are sorted in ascending order. Otherwise, specify an order of "desc" for
descending or "asc" for ascending sort order of corresponding values.
Arguments
collection (Array|Object): The collection to iterate over.[iteratees=[_.identity]] (Function[]|Object[]|string[]): The iteratees to sort by.[orders] (string[]): The sort orders of iteratees.
Returns
(Array): Returns the new sorted array.
Example
var users = [
{ 'user': 'fred', 'age': 48 },
{ 'user': 'barney', 'age': 34 },
{ 'user': 'fred', 'age': 42 },
{ 'user': 'barney', 'age': 36 }
];
// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(users, ['user', 'age'], ['asc', 'desc']);
// → objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
_.partition(collection, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates an array of elements split into two groups, the first of which
contains elements predicate returns truthy for, the second of which
contains elements predicate returns falsey for. The predicate is
invoked with one argument: (value).
Arguments
collection (Array|Object): The collection to iterate over.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the array of grouped elements.
Example
var users = [
{ 'user': 'barney', 'age': 36, 'active': false },
{ 'user': 'fred', 'age': 40, 'active': true },
{ 'user': 'pebbles', 'age': 1, 'active': false }
];
_.partition(users, function(o) { return o.active; });
// → objects for [['fred'], ['barney', 'pebbles']]
// The `_.matches` iteratee shorthand.
_.partition(users, { 'age': 1, 'active': false });
// → objects for [['pebbles'], ['barney', 'fred']]
// The `_.matchesProperty` iteratee shorthand.
_.partition(users, ['active', false]);
// → objects for [['barney', 'pebbles'], ['fred']]
// The `_.property` iteratee shorthand.
_.partition(users, 'active');
// → objects for [['fred'], ['barney', 'pebbles']]
_.reduce(collection, [iteratee=_.identity], [accumulator])
# Ⓢ Ⓣ Ⓝ
Reduces collection to a value which is the accumulated result of running
each element in collection through iteratee, where each successive
invocation is supplied the return value of the previous. If accumulator
is not given the first element of collection is used as the initial
value. The iteratee is invoked with four arguments:
(accumulator, value, index|key, collection).
Many lodash methods are guarded to work as iteratees for methods like
_.reduce, _.reduceRight, and _.transform.
The guarded methods are:
assign, defaults, defaultsDeep, includes, merge, orderBy,
and sortBy
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.[accumulator] (*): The initial value.
Returns
(*): Returns the accumulated value.
Example
_.reduce([1, 2], function(sum, n) {
return sum + n;
}, 0);
// → 3
_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
(result[value] || (result[value] = [])).push(key);
return result;
}, {});
// → { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)
_.reduceRight(collection, [iteratee=_.identity], [accumulator])
# Ⓢ Ⓣ Ⓝ
This method is like _.reduce except that it iterates over elements of
collection from right to left.
Arguments
collection (Array|Object): The collection to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.[accumulator] (*): The initial value.
Returns
(*): Returns the accumulated value.
Example
var array = [[0, 1], [2, 3], [4, 5]];
_.reduceRight(array, function(flattened, other) {
return flattened.concat(other);
}, []);
// → [4, 5, 2, 3, 0, 1]
_.reject(collection, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
The opposite of _.filter; this method returns the elements of collection
that predicate does not return truthy for.
Arguments
collection (Array|Object): The collection to iterate over.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Array): Returns the new filtered array.
Example
var users = [
{ 'user': 'barney', 'age': 36, 'active': false },
{ 'user': 'fred', 'age': 40, 'active': true }
];
_.reject(users, function(o) { return !o.active; });
// → objects for ['fred']
// The `_.matches` iteratee shorthand.
_.reject(users, { 'age': 40, 'active': true });
// → objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.reject(users, ['active', false]);
// → objects for ['fred']
// The `_.property` iteratee shorthand.
_.reject(users, 'active');
// → objects for ['barney']
_.sample(collection)
# Ⓢ Ⓣ Ⓝ
Gets a random element from collection.
Arguments
collection (Array|Object): The collection to sample.
Returns
(*): Returns the random element.
Example
_.sample([1, 2, 3, 4]);
// → 2
_.sampleSize(collection, [n=0])
# Ⓢ Ⓣ Ⓝ
Gets n random elements at unique keys from collection up to the
size of collection.
Arguments
collection (Array|Object): The collection to sample.[n=0] (number): The number of elements to sample.
Returns
(Array): Returns the random elements.
Example
_.sampleSize([1, 2, 3], 2);
// → [3, 1]
_.sampleSize([1, 2, 3], 4);
// → [2, 3, 1]
_.shuffle(collection)
# Ⓢ Ⓣ Ⓝ
Creates an array of shuffled values, using a version of the
Fisher-Yates shuffle.
Arguments
collection (Array|Object): The collection to shuffle.
Returns
(Array): Returns the new shuffled array.
Example
_.shuffle([1, 2, 3, 4]);
// → [4, 1, 3, 2]
_.size(collection)
# Ⓢ Ⓣ Ⓝ
Gets the size of collection by returning its length for array-like
values or the number of own enumerable properties for objects.
Arguments
collection (Array|Object): The collection to inspect.
Returns
(number): Returns the collection size.
Example
_.size([1, 2, 3]);
// → 3
_.size({ 'a': 1, 'b': 2 });
// → 2
_.size('pebbles');
// → 7
_.some(collection, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Checks if predicate returns truthy for any element of collection.
Iteration is stopped once predicate returns truthy. The predicate is
invoked with three arguments: (value, index|key, collection).
Arguments
collection (Array|Object): The collection to iterate over.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(boolean): Returns true if any element passes the predicate check, else false.
Example
_.some([null, 0, 'yes', false], Boolean);
// → true
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false }
];
// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// → false
// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// → true
// The `_.property` iteratee shorthand.
_.some(users, 'active');
// → true
_.sortBy(collection, [iteratees=[_.identity]])
# Ⓢ Ⓣ Ⓝ
Creates an array of elements, sorted in ascending order by the results of
running each element in a collection through each iteratee. This method
performs a stable sort, that is, it preserves the original sort order of
equal elements. The iteratees are invoked with one argument: (value).
Arguments
collection (Array|Object): The collection to iterate over.[iteratees=[_.identity]] (…(Function|Function[]|Object|Object[]|string|string[]): The iteratees to sort by, specified individually or in arrays.
Returns
(Array): Returns the new sorted array.
Example
var users = [
{ 'user': 'fred', 'age': 48 },
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 42 },
{ 'user': 'barney', 'age': 34 }
];
_.sortBy(users, function(o) { return o.user; });
// → objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
_.sortBy(users, ['user', 'age']);
// → objects for [['barney', 34], ['barney', 36], ['fred', 42], ['fred', 48]]
_.sortBy(users, 'user', function(o) {
return Math.floor(o.age / 10);
});
// → objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
“Function” Methods
_.after(n, func)
# Ⓢ Ⓣ Ⓝ
The opposite of _.before; this method creates a function that invokes
func once it’s called n or more times.
Arguments
n (number): The number of calls before func is invoked.func (Function): The function to restrict.
Returns
(Function): Returns the new restricted function.
Example
var saves = ['profile', 'settings'];
var done = _.after(saves.length, function() {
console.log('done saving!');
});
_.forEach(saves, function(type) {
asyncSave({ 'type': type, 'complete': done });
});
// → logs 'done saving!' after the two async saves have completed
_.ary(func, [n=func.length])
# Ⓢ Ⓣ Ⓝ
Creates a function that accepts up to n arguments, ignoring any
additional arguments.
Arguments
func (Function): The function to cap arguments for.[n=func.length] (number): The arity cap.
Returns
(Function): Returns the new function.
Example
_.map(['6', '8', '10'], _.ary(parseInt, 1));
// → [6, 8, 10]
_.before(n, func)
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func, with the this binding and arguments
of the created function, while it’s called less than n times. Subsequent
calls to the created function return the result of the last func invocation.
Arguments
n (number): The number of calls at which func is no longer invoked.func (Function): The function to restrict.
Returns
(Function): Returns the new restricted function.
Example
jQuery(element).on('click', _.before(5, addContactToList));
// → allows adding up to 4 contacts to the list
_.bind(func, thisArg, [partials])
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func with the this binding of thisArg
and prepends any additional _.bind arguments to those provided to the
bound function.
The _.bind.placeholder value, which defaults to _ in monolithic builds,
may be used as a placeholder for partially applied arguments.
Note: Unlike native Function#bind this method doesn’t set the "length"
property of bound functions.
Arguments
func (Function): The function to bind.thisArg (*): The this binding of func.[partials] (…*): The arguments to be partially applied.
Returns
(Function): Returns the new bound function.
Example
var greet = function(greeting, punctuation) {
return greeting + ' ' + this.user + punctuation;
};
var object = { 'user': 'fred' };
var bound = _.bind(greet, object, 'hi');
bound('!');
// → 'hi fred!'
// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// → 'hi fred!'
_.bindKey(object, key, [partials])
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes the method at object[key] and prepends
any additional _.bindKey arguments to those provided to the bound function.
This method differs from _.bind by allowing bound functions to reference
methods that may be redefined or don’t yet exist.
See Peter Michaux’s article
for more details.
The _.bindKey.placeholder value, which defaults to _ in monolithic
builds, may be used as a placeholder for partially applied arguments.
Arguments
object (Object): The object to invoke the method on.key (string): The key of the method.[partials] (…*): The arguments to be partially applied.
Returns
(Function): Returns the new bound function.
Example
var object = {
'user': 'fred',
'greet': function(greeting, punctuation) {
return greeting + ' ' + this.user + punctuation;
}
};
var bound = _.bindKey(object, 'greet', 'hi');
bound('!');
// → 'hi fred!'
object.greet = function(greeting, punctuation) {
return greeting + 'ya ' + this.user + punctuation;
};
bound('!');
// → 'hiya fred!'
// Bound with placeholders.
var bound = _.bindKey(object, 'greet', _, '!');
bound('hi');
// → 'hiya fred!'
_.curry(func, [arity=func.length])
# Ⓢ Ⓣ Ⓝ
Creates a function that accepts arguments of func and either invokes
func returning its result, if at least arity number of arguments have
been provided, or returns a function that accepts the remaining func
arguments, and so on. The arity of func may be specified if func.length
is not sufficient.
The _.curry.placeholder value, which defaults to _ in monolithic builds,
may be used as a placeholder for provided arguments.
Note: This method doesn’t set the "length" property of curried functions.
Arguments
func (Function): The function to curry.[arity=func.length] (number): The arity of func.
Returns
(Function): Returns the new curried function.
Example
var abc = function(a, b, c) {
return [a, b, c];
};
var curried = _.curry(abc);
curried(1)(2)(3);
// → [1, 2, 3]
curried(1, 2)(3);
// → [1, 2, 3]
curried(1, 2, 3);
// → [1, 2, 3]
// Curried with placeholders.
curried(1)(_, 3)(2);
// → [1, 2, 3]
_.curryRight(func, [arity=func.length])
# Ⓢ Ⓣ Ⓝ
This method is like _.curry except that arguments are applied to func
in the manner of _.partialRight instead of _.partial.
The _.curryRight.placeholder value, which defaults to _ in monolithic
builds, may be used as a placeholder for provided arguments.
Note: This method doesn’t set the "length" property of curried functions.
Arguments
func (Function): The function to curry.[arity=func.length] (number): The arity of func.
Returns
(Function): Returns the new curried function.
Example
var abc = function(a, b, c) {
return [a, b, c];
};
var curried = _.curryRight(abc);
curried(3)(2)(1);
// → [1, 2, 3]
curried(2, 3)(1);
// → [1, 2, 3]
curried(1, 2, 3);
// → [1, 2, 3]
// Curried with placeholders.
curried(3)(1, _)(2);
// → [1, 2, 3]
_.debounce(func, [wait=0], [options])
# Ⓢ Ⓣ Ⓝ
Creates a debounced function that delays invoking func until after wait
milliseconds have elapsed since the last time the debounced function was
invoked. The debounced function comes with a cancel method to cancel
delayed func invocations and a flush method to immediately invoke them.
Provide an options object to indicate whether func should be invoked on
the leading and/or trailing edge of the wait timeout. The func is invoked
with the last arguments provided to the debounced function. Subsequent calls
to the debounced function return the result of the last func invocation.
Note: If leading and trailing options are true, func is invoked
on the trailing edge of the timeout only if the debounced function is
invoked more than once during the wait timeout.
See David Corbacho’s article
for details over the differences between _.debounce and _.throttle.
Arguments
func (Function): The function to debounce.[wait=0] (number): The number of milliseconds to delay.[options] (Object): The options object.[options.leading=false] (boolean): Specify invoking on the leading edge of the timeout.[options.maxWait] (number): The maximum time func is allowed to be delayed before it’s invoked.[options.trailing=true] (boolean): Specify invoking on the trailing edge of the timeout.
Returns
(Function): Returns the new debounced function.
Example
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(calculateLayout, 150));
// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce(sendMail, 300, {
'leading': true,
'trailing': false
}));
// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);
// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);
_.defer(func, [args])
# Ⓢ Ⓣ Ⓝ
Defers invoking the func until the current call stack has cleared. Any
additional arguments are provided to func when it’s invoked.
Arguments
func (Function): The function to defer.[args] (…*): The arguments to invoke func with.
Returns
(number): Returns the timer id.
Example
_.defer(function(text) {
console.log(text);
}, 'deferred');
// → logs 'deferred' after one or more milliseconds
_.delay(func, wait, [args])
# Ⓢ Ⓣ Ⓝ
Invokes func after wait milliseconds. Any additional arguments are
provided to func when it’s invoked.
Arguments
func (Function): The function to delay.wait (number): The number of milliseconds to delay invocation.[args] (…*): The arguments to invoke func with.
Returns
(number): Returns the timer id.
Example
_.delay(function(text) {
console.log(text);
}, 1000, 'later');
// → logs 'later' after one second
_.flip(func)
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func with arguments reversed.
Arguments
func (Function): The function to flip arguments for.
Returns
(Function): Returns the new function.
Example
var flipped = _.flip(function() {
return _.toArray(arguments);
});
flipped('a', 'b', 'c', 'd');
// → ['d', 'c', 'b', 'a']
_.memoize(func, [resolver])
# Ⓢ Ⓣ Ⓝ
Creates a function that memoizes the result of func. If resolver is
provided it determines the cache key for storing the result based on the
arguments provided to the memoized function. By default, the first argument
provided to the memoized function is used as the map cache key. The func
is invoked with the this binding of the memoized function.
Note: The cache is exposed as the cache property on the memoized
function. Its creation may be customized by replacing the _.memoize.Cache
constructor with one whose instances implement the Map
method interface of delete, get, has, and set.
Arguments
func (Function): The function to have its output memoized.[resolver] (Function): The function to resolve the cache key.
Returns
(Function): Returns the new memoizing function.
Example
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };
var values = _.memoize(_.values);
values(object);
// → [1, 2]
values(other);
// → [3, 4]
object.a = 2;
values(object);
// → [1, 2]
// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// → ['a', 'b']
// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;
_.negate(predicate)
# Ⓢ Ⓣ Ⓝ
Creates a function that negates the result of the predicate func. The
func predicate is invoked with the this binding and arguments of the
created function.
Arguments
predicate (Function): The predicate to negate.
Returns
(Function): Returns the new function.
Example
function isEven(n) {
return n % 2 == 0;
}
_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// → [1, 3, 5]
_.once(func)
# Ⓢ Ⓣ Ⓝ
Creates a function that is restricted to invoking func once. Repeat calls
to the function return the value of the first invocation. The func is
invoked with the this binding and arguments of the created function.
Arguments
func (Function): The function to restrict.
Returns
(Function): Returns the new restricted function.
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// `initialize` invokes `createApplication` once
_.overArgs(func, [transforms])
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func with arguments transformed by
corresponding transforms.
Arguments
func (Function): The function to wrap.[transforms] (…(Function|Function[]): The functions to transform arguments, specified individually or in arrays.
Returns
(Function): Returns the new function.
Example
function doubled(n) {
return n * 2;
}
function square(n) {
return n * n;
}
var func = _.overArgs(function(x, y) {
return [x, y];
}, square, doubled);
func(9, 3);
// → [81, 6]
func(10, 5);
// → [100, 10]
_.partial(func, [partials])
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func with partial arguments prepended
to those provided to the new function. This method is like _.bind except
it does not alter the this binding.
The _.partial.placeholder value, which defaults to _ in monolithic
builds, may be used as a placeholder for partially applied arguments.
Note: This method doesn’t set the "length" property of partially
applied functions.
Arguments
func (Function): The function to partially apply arguments to.[partials] (…*): The arguments to be partially applied.
Returns
(Function): Returns the new partially applied function.
Example
var greet = function(greeting, name) {
return greeting + ' ' + name;
};
var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// → 'hello fred'
// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// → 'hi fred'
_.partialRight(func, [partials])
# Ⓢ Ⓣ Ⓝ
This method is like _.partial except that partially applied arguments
are appended to those provided to the new function.
The _.partialRight.placeholder value, which defaults to _ in monolithic
builds, may be used as a placeholder for partially applied arguments.
Note: This method doesn’t set the "length" property of partially
applied functions.
Arguments
func (Function): The function to partially apply arguments to.[partials] (…*): The arguments to be partially applied.
Returns
(Function): Returns the new partially applied function.
Example
var greet = function(greeting, name) {
return greeting + ' ' + name;
};
var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// → 'hi fred'
// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// → 'hello fred'
_.rearg(func, indexes)
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func with arguments arranged according
to the specified indexes where the argument value at the first index is
provided as the first argument, the argument value at the second index is
provided as the second argument, and so on.
Arguments
func (Function): The function to rearrange arguments for.indexes (…(number|number[]): The arranged argument indexes, specified individually or in arrays.
Returns
(Function): Returns the new function.
Example
var rearged = _.rearg(function(a, b, c) {
return [a, b, c];
}, 2, 0, 1);
rearged('b', 'c', 'a')
// → ['a', 'b', 'c']
_.rest(func, [start=func.length-1])
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func with the this binding of the
created function and arguments from start and beyond provided as an array.
Note: This method is based on the rest parameter.
Arguments
func (Function): The function to apply a rest parameter to.[start=func.length-1] (number): The start position of the rest parameter.
Returns
(Function): Returns the new function.
Example
var say = _.rest(function(what, names) {
return what + ' ' + _.initial(names).join(', ') +
(_.size(names) > 1 ? ', & ' : '') + _.last(names);
});
say('hello', 'fred', 'barney', 'pebbles');
// → 'hello fred, barney, & pebbles'
_.spread(func, [start=0])
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func with the this binding of the created
function and an array of arguments much like Function#apply.
Note: This method is based on the spread operator.
Arguments
func (Function): The function to spread arguments over.[start=0] (number): The start position of the spread.
Returns
(Function): Returns the new function.
Example
var say = _.spread(function(who, what) {
return who + ' says ' + what;
});
say(['fred', 'hello']);
// → 'fred says hello'
var numbers = Promise.all([
Promise.resolve(40),
Promise.resolve(36)
]);
numbers.then(_.spread(function(x, y) {
return x + y;
}));
// → a Promise of 76
_.throttle(func, [wait=0], [options])
# Ⓢ Ⓣ Ⓝ
Creates a throttled function that only invokes func at most once per
every wait milliseconds. The throttled function comes with a cancel
method to cancel delayed func invocations and a flush method to
immediately invoke them. Provide an options object to indicate whether
func should be invoked on the leading and/or trailing edge of the wait
timeout. The func is invoked with the last arguments provided to the
throttled function. Subsequent calls to the throttled function return the
result of the last func invocation.
Note: If leading and trailing options are true, func is invoked
on the trailing edge of the timeout only if the throttled function is
invoked more than once during the wait timeout.
See David Corbacho’s article
for details over the differences between _.throttle and _.debounce.
Arguments
func (Function): The function to throttle.[wait=0] (number): The number of milliseconds to throttle invocations to.[options] (Object): The options object.[options.leading=true] (boolean): Specify invoking on the leading edge of the timeout.[options.trailing=true] (boolean): Specify invoking on the trailing edge of the timeout.
Returns
(Function): Returns the new throttled function.
Example
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(updatePosition, 100));
// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);
// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);
_.unary(func)
# Ⓢ Ⓣ Ⓝ
Creates a function that accepts up to one argument, ignoring any
additional arguments.
Arguments
func (Function): The function to cap arguments for.
Returns
(Function): Returns the new function.
Example
_.map(['6', '8', '10'], _.unary(parseInt));
// → [6, 8, 10]
_.wrap(value, [wrapper=identity])
# Ⓢ Ⓣ Ⓝ
Creates a function that provides value to the wrapper function as its
first argument. Any additional arguments provided to the function are
appended to those provided to the wrapper function. The wrapper is invoked
with the this binding of the created function.
Arguments
value (*): The value to wrap.[wrapper=identity] (Function): The wrapper function.
Returns
(Function): Returns the new function.
Example
var p = _.wrap(_.escape, function(func, text) {
return '<p>' + func(text) + '<p>';
});
p('fred, barney, & pebbles');
// → '<p>fred, barney, & pebbles<p>'
“Lang” Methods
_.castArray(value)
# Ⓢ Ⓣ Ⓝ
Casts value as an array if it’s not one.
Arguments
value (*): The value to inspect.
Returns
(Array): Returns the cast array.
Example
_.castArray(1);
// → [1]
_.castArray({ 'a': 1 });
// → [{ 'a': 1 }]
_.castArray('abc');
// → ['abc']
_.castArray(null);
// → [null]
_.castArray(undefined);
// → [undefined]
_.castArray();
// → []
var array = [1, 2, 3];
console.log(_.castArray(array) === array);
// → true
_.clone(value)
# Ⓢ Ⓣ Ⓝ
Creates a shallow clone of value.
Note: This method is loosely based on the
structured clone algorithm
and supports cloning arrays, array buffers, booleans, date objects, maps,
numbers, Object objects, regexes, sets, strings, symbols, and typed
arrays. The own enumerable properties of arguments objects are cloned
as plain objects. An empty object is returned for uncloneable values such
as error objects, functions, DOM nodes, and WeakMaps.
Arguments
value (*): The value to clone.
Returns
(*): Returns the cloned value.
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];
var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// → true
_.cloneDeep(value)
# Ⓢ Ⓣ Ⓝ
This method is like _.clone except that it recursively clones value.
Arguments
value (*): The value to recursively clone.
Returns
(*): Returns the deep cloned value.
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];
var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// → false
_.cloneDeepWith(value, [customizer])
# Ⓢ Ⓣ Ⓝ
This method is like _.cloneWith except that it recursively clones value.
Arguments
value (*): The value to recursively clone.[customizer] (Function): The function to customize cloning.
Returns
(*): Returns the deep cloned value.
Example
function customizer(value) {
if (_.isElement(value)) {
return value.cloneNode(true);
}
}
var el = _.cloneDeepWith(document.body, customizer);
console.log(el === document.body);
// → false
console.log(el.nodeName);
// → 'BODY'
console.log(el.childNodes.length);
// → 20
_.cloneWith(value, [customizer])
# Ⓢ Ⓣ Ⓝ
This method is like _.clone except that it accepts customizer which
is invoked to produce the cloned value. If customizer returns undefined
cloning is handled by the method instead. The customizer is invoked with
up to four arguments; (value [, index|key, object, stack]).
Arguments
value (*): The value to clone.[customizer] (Function): The function to customize cloning.
Returns
(*): Returns the cloned value.
Example
function customizer(value) {
if (_.isElement(value)) {
return value.cloneNode(false);
}
}
var el = _.cloneWith(document.body, customizer);
console.log(el === document.body);
// → false
console.log(el.nodeName);
// → 'BODY'
console.log(el.childNodes.length);
// → 0
_.eq(value, other)
# Ⓢ Ⓣ Ⓝ
Performs a SameValueZero
comparison between two values to determine if they are equivalent.
Arguments
value (*): The value to compare.other (*): The other value to compare.
Returns
(boolean): Returns true if the values are equivalent, else false.
Example
var object = { 'user': 'fred' };
var other = { 'user': 'fred' };
_.eq(object, object);
// → true
_.eq(object, other);
// → false
_.eq('a', 'a');
// → true
_.eq('a', Object('a'));
// → false
_.eq(NaN, NaN);
// → true
_.gt(value, other)
# Ⓢ Ⓣ Ⓝ
Checks if value is greater than other.
Arguments
value (*): The value to compare.other (*): The other value to compare.
Returns
(boolean): Returns true if value is greater than other, else false.
Example
_.gt(3, 1);
// → true
_.gt(3, 3);
// → false
_.gt(1, 3);
// → false
_.gte(value, other)
# Ⓢ Ⓣ Ⓝ
Checks if value is greater than or equal to other.
Arguments
value (*): The value to compare.other (*): The other value to compare.
Returns
(boolean): Returns true if value is greater than or equal to other, else false.
Example
_.gte(3, 1);
// → true
_.gte(3, 3);
// → true
_.gte(1, 3);
// → false
_.isArguments(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is likely an arguments object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isArguments(function() { return arguments; }());
// → true
_.isArguments([1, 2, 3]);
// → false
_.isArray(value)
# Ⓢ Ⓣ Ⓝ
({Function}): Checks if value is classified as an Array object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isArray([1, 2, 3]);
// → true
_.isArray(document.body.children);
// → false
_.isArray('abc');
// → false
_.isArray(_.noop);
// → false
_.isArrayBuffer(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as an ArrayBuffer object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isArrayBuffer(new ArrayBuffer(2));
// → true
_.isArrayBuffer(new Array(2));
// → false
_.isArrayLike(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is array-like. A value is considered array-like if it’s
not a function and has a value.length that’s an integer greater than or
equal to 0 and less than or equal to Number.MAX_SAFE_INTEGER.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is array-like, else false.
Example
_.isArrayLike([1, 2, 3]);
// → true
_.isArrayLike(document.body.children);
// → true
_.isArrayLike('abc');
// → true
_.isArrayLike(_.noop);
// → false
_.isArrayLikeObject(value)
# Ⓢ Ⓣ Ⓝ
This method is like _.isArrayLike except that it also checks if value
is an object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is an array-like object, else false.
Example
_.isArrayLikeObject([1, 2, 3]);
// → true
_.isArrayLikeObject(document.body.children);
// → true
_.isArrayLikeObject('abc');
// → false
_.isArrayLikeObject(_.noop);
// → false
_.isBoolean(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a boolean primitive or object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isBoolean(false);
// → true
_.isBoolean(null);
// → false
_.isBuffer(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is a buffer.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is a buffer, else false.
Example
_.isBuffer(new Buffer(2));
// → true
_.isBuffer(new Uint8Array(2));
// → false
_.isDate(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a Date object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isDate(new Date);
// → true
_.isDate('Mon April 23 2012');
// → false
_.isElement(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is likely a DOM element.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is a DOM element, else false.
Example
_.isElement(document.body);
// → true
_.isElement('<body>');
// → false
_.isEmpty(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is an empty collection or object. A value is considered
empty if it’s an arguments object, array, string, or jQuery-like collection
with a length of 0 or has no own enumerable properties.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is empty, else false.
Example
_.isEmpty(null);
// → true
_.isEmpty(true);
// → true
_.isEmpty(1);
// → true
_.isEmpty([1, 2, 3]);
// → false
_.isEmpty({ 'a': 1 });
// → false
_.isEqual(value, other)
# Ⓢ Ⓣ Ⓝ
Performs a deep comparison between two values to determine if they are
equivalent.
Note: This method supports comparing arrays, array buffers, booleans,
date objects, error objects, maps, numbers, Object objects, regexes,
sets, strings, symbols, and typed arrays. Object objects are compared
by their own, not inherited, enumerable properties. Functions and DOM
nodes are not supported.
Arguments
value (*): The value to compare.other (*): The other value to compare.
Returns
(boolean): Returns true if the values are equivalent, else false.
Example
var object = { 'user': 'fred' };
var other = { 'user': 'fred' };
_.isEqual(object, other);
// → true
object === other;
// → false
_.isEqualWith(value, other, [customizer])
# Ⓢ Ⓣ Ⓝ
This method is like _.isEqual except that it accepts customizer which
is invoked to compare values. If customizer returns undefined comparisons
are handled by the method instead. The customizer is invoked with up to
six arguments: (objValue, othValue [, index|key, object, other, stack]).
Arguments
value (*): The value to compare.other (*): The other value to compare.[customizer] (Function): The function to customize comparisons.
Returns
(boolean): Returns true if the values are equivalent, else false.
Example
function isGreeting(value) {
return /^h(?:i|ello)$/.test(value);
}
function customizer(objValue, othValue) {
if (isGreeting(objValue) && isGreeting(othValue)) {
return true;
}
}
var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];
_.isEqualWith(array, other, customizer);
// → true
_.isError(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is an Error, EvalError, RangeError, ReferenceError,
SyntaxError, TypeError, or URIError object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is an error object, else false.
Example
_.isError(new Error);
// → true
_.isError(Error);
// → false
_.isFinite(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is a finite primitive number.
Note: This method is based on Number.isFinite.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is a finite number, else false.
Example
_.isFinite(3);
// → true
_.isFinite(Number.MAX_VALUE);
// → true
_.isFinite(3.14);
// → true
_.isFinite(Infinity);
// → false
_.isFunction(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a Function object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isFunction(_);
// → true
_.isFunction(/abc/);
// → false
_.isInteger(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is an integer.
Note: This method is based on Number.isInteger.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is an integer, else false.
Example
_.isInteger(3);
// → true
_.isInteger(Number.MIN_VALUE);
// → false
_.isInteger(Infinity);
// → false
_.isInteger('3');
// → false
_.isLength(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is a valid array-like length.
Note: This function is loosely based on ToLength.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is a valid length, else false.
Example
_.isLength(3);
// → true
_.isLength(Number.MIN_VALUE);
// → false
_.isLength(Infinity);
// → false
_.isLength('3');
// → false
_.isMap(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a Map object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isMap(new Map);
// → true
_.isMap(new WeakMap);
// → false
_.isMatch(object, source)
# Ⓢ Ⓣ Ⓝ
Performs a partial deep comparison between object and source to
determine if object contains equivalent property values. This method is
equivalent to a _.matches function when source is partially applied.
Note: This method supports comparing the same values as _.isEqual.
Arguments
object (Object): The object to inspect.source (Object): The object of property values to match.
Returns
(boolean): Returns true if object is a match, else false.
Example
var object = { 'user': 'fred', 'age': 40 };
_.isMatch(object, { 'age': 40 });
// → true
_.isMatch(object, { 'age': 36 });
// → false
_.isMatchWith(object, source, [customizer])
# Ⓢ Ⓣ Ⓝ
This method is like _.isMatch except that it accepts customizer which
is invoked to compare values. If customizer returns undefined comparisons
are handled by the method instead. The customizer is invoked with five
arguments: (objValue, srcValue, index|key, object, source).
Arguments
object (Object): The object to inspect.source (Object): The object of property values to match.[customizer] (Function): The function to customize comparisons.
Returns
(boolean): Returns true if object is a match, else false.
Example
function isGreeting(value) {
return /^h(?:i|ello)$/.test(value);
}
function customizer(objValue, srcValue) {
if (isGreeting(objValue) && isGreeting(srcValue)) {
return true;
}
}
var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };
_.isMatchWith(object, source, customizer);
// → true
_.isNaN(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is NaN.
Note: This method is not the same as isNaN
which returns true for undefined and other non-numeric values.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is NaN, else false.
Example
_.isNaN(NaN);
// → true
_.isNaN(new Number(NaN));
// → true
isNaN(undefined);
// → true
_.isNaN(undefined);
// → false
_.isNative(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is a native function.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is a native function, else false.
Example
_.isNative(Array.prototype.push);
// → true
_.isNative(_);
// → false
_.isNil(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is null or undefined.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is nullish, else false.
Example
_.isNil(null);
// → true
_.isNil(void 0);
// → true
_.isNil(NaN);
// → false
_.isNull(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is null.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is null, else false.
Example
_.isNull(null);
// → true
_.isNull(void 0);
// → false
_.isNumber(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a Number primitive or object.
Note: To exclude Infinity, -Infinity, and NaN, which are classified
as numbers, use the _.isFinite method.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isNumber(3);
// → true
_.isNumber(Number.MIN_VALUE);
// → true
_.isNumber(Infinity);
// → true
_.isNumber('3');
// → false
_.isObject(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is the language type of Object.
(e.g. arrays, functions, objects, regexes, new Number(0), and new String(''))
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is an object, else false.
Example
_.isObject({});
// → true
_.isObject([1, 2, 3]);
// → true
_.isObject(_.noop);
// → true
_.isObject(null);
// → false
_.isObjectLike(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is object-like. A value is object-like if it’s not null
and has a typeof result of "object".
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is object-like, else false.
Example
_.isObjectLike({});
// → true
_.isObjectLike([1, 2, 3]);
// → true
_.isObjectLike(_.noop);
// → false
_.isObjectLike(null);
// → false
_.isPlainObject(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is a plain object, that is, an object created by the
Object constructor or one with a [[Prototype]] of null.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is a plain object, else false.
Example
function Foo() {
this.a = 1;
}
_.isPlainObject(new Foo);
// → false
_.isPlainObject([1, 2, 3]);
// → false
_.isPlainObject({ 'x': 0, 'y': 0 });
// → true
_.isPlainObject(Object.create(null));
// → true
_.isRegExp(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a RegExp object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isRegExp(/abc/);
// → true
_.isRegExp('/abc/');
// → false
_.isSafeInteger(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is a safe integer. An integer is safe if it’s an IEEE-754
double precision number which isn’t the result of a rounded unsafe integer.
Note: This method is based on Number.isSafeInteger.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is a safe integer, else false.
Example
_.isSafeInteger(3);
// → true
_.isSafeInteger(Number.MIN_VALUE);
// → false
_.isSafeInteger(Infinity);
// → false
_.isSafeInteger('3');
// → false
_.isSet(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a Set object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isSet(new Set);
// → true
_.isSet(new WeakSet);
// → false
_.isString(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a String primitive or object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isString('abc');
// → true
_.isString(1);
// → false
_.isSymbol(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a Symbol primitive or object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isSymbol(Symbol.iterator);
// → true
_.isSymbol('abc');
// → false
_.isTypedArray(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a typed array.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isTypedArray(new Uint8Array);
// → true
_.isTypedArray([]);
// → false
_.isUndefined(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is undefined.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is undefined, else false.
Example
_.isUndefined(void 0);
// → true
_.isUndefined(null);
// → false
_.isWeakMap(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a WeakMap object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isWeakMap(new WeakMap);
// → true
_.isWeakMap(new Map);
// → false
_.isWeakSet(value)
# Ⓢ Ⓣ Ⓝ
Checks if value is classified as a WeakSet object.
Arguments
value (*): The value to check.
Returns
(boolean): Returns true if value is correctly classified, else false.
Example
_.isWeakSet(new WeakSet);
// → true
_.isWeakSet(new Set);
// → false
_.lt(value, other)
# Ⓢ Ⓣ Ⓝ
Checks if value is less than other.
Arguments
value (*): The value to compare.other (*): The other value to compare.
Returns
(boolean): Returns true if value is less than other, else false.
Example
_.lt(1, 3);
// → true
_.lt(3, 3);
// → false
_.lt(3, 1);
// → false
_.lte(value, other)
# Ⓢ Ⓣ Ⓝ
Checks if value is less than or equal to other.
Arguments
value (*): The value to compare.other (*): The other value to compare.
Returns
(boolean): Returns true if value is less than or equal to other, else false.
Example
_.lte(1, 3);
// → true
_.lte(3, 3);
// → true
_.lte(3, 1);
// → false
_.toArray(value)
# Ⓢ Ⓣ Ⓝ
Converts value to an array.
Arguments
value (*): The value to convert.
Returns
(Array): Returns the converted array.
Example
_.toArray({ 'a': 1, 'b': 2 });
// → [1, 2]
_.toArray('abc');
// → ['a', 'b', 'c']
_.toArray(1);
// → []
_.toArray(null);
// → []
_.toInteger(value)
# Ⓢ Ⓣ Ⓝ
Converts value to an integer.
Note: This function is loosely based on ToInteger.
Arguments
value (*): The value to convert.
Returns
(number): Returns the converted integer.
Example
_.toInteger(3);
// → 3
_.toInteger(Number.MIN_VALUE);
// → 0
_.toInteger(Infinity);
// → 1.7976931348623157e+308
_.toInteger('3');
// → 3
_.toLength(value)
# Ⓢ Ⓣ Ⓝ
Converts value to an integer suitable for use as the length of an
array-like object.
Note: This method is based on ToLength.
Arguments
value (*): The value to convert.
Returns
(number): Returns the converted integer.
Example
_.toLength(3);
// → 3
_.toLength(Number.MIN_VALUE);
// → 0
_.toLength(Infinity);
// → 4294967295
_.toLength('3');
// → 3
_.toNumber(value)
# Ⓢ Ⓣ Ⓝ
Converts value to a number.
Arguments
value (*): The value to process.
Returns
(number): Returns the number.
Example
_.toNumber(3);
// → 3
_.toNumber(Number.MIN_VALUE);
// → 5e-324
_.toNumber(Infinity);
// → Infinity
_.toNumber('3');
// → 3
_.toPlainObject(value)
# Ⓢ Ⓣ Ⓝ
Converts value to a plain object flattening inherited enumerable
properties of value to own properties of the plain object.
Arguments
value (*): The value to convert.
Returns
(Object): Returns the converted plain object.
Example
function Foo() {
this.b = 2;
}
Foo.prototype.c = 3;
_.assign({ 'a': 1 }, new Foo);
// → { 'a': 1, 'b': 2 }
_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// → { 'a': 1, 'b': 2, 'c': 3 }
_.toSafeInteger(value)
# Ⓢ Ⓣ Ⓝ
Converts value to a safe integer. A safe integer can be compared and
represented correctly.
Arguments
value (*): The value to convert.
Returns
(number): Returns the converted integer.
Example
_.toSafeInteger(3);
// → 3
_.toSafeInteger(Number.MIN_VALUE);
// → 0
_.toSafeInteger(Infinity);
// → 9007199254740991
_.toSafeInteger('3');
// → 3
_.toString(value)
# Ⓢ Ⓣ Ⓝ
Converts value to a string if it’s not one. An empty string is returned
for null and undefined values. The sign of -0 is preserved.
Arguments
value (*): The value to process.
Returns
(string): Returns the string.
Example
_.toString(null);
// → ''
_.toString(-0);
// → '-0'
_.toString([1, 2, 3]);
// → '1,2,3'
“Object” Methods
_.assign(object, [sources])
# Ⓢ Ⓣ Ⓝ
Assigns own enumerable properties of source objects to the destination
object. Source objects are applied from left to right. Subsequent sources
overwrite property assignments of previous sources.
Note: This method mutates object and is loosely based on
Object.assign.
Arguments
object (Object): The destination object.[sources] (…Object): The source objects.
Returns
(Object): Returns object.
Example
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
_.assign({ 'a': 1 }, new Foo, new Bar);
// → { 'a': 1, 'c': 3, 'e': 5 }
_.assignIn(object, [sources])
# Ⓢ Ⓣ Ⓝ
This method is like _.assign except that it iterates over own and
inherited source properties.
Note: This method mutates object.
Aliases
_.extend
Arguments
object (Object): The destination object.[sources] (…Object): The source objects.
Returns
(Object): Returns object.
Example
function Foo() {
this.b = 2;
}
function Bar() {
this.d = 4;
}
Foo.prototype.c = 3;
Bar.prototype.e = 5;
_.assignIn({ 'a': 1 }, new Foo, new Bar);
// → { 'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5 }
_.assignInWith(object, sources, [customizer])
# Ⓢ Ⓣ Ⓝ
This method is like _.assignIn except that it accepts customizer which
is invoked to produce the assigned values. If customizer returns undefined
assignment is handled by the method instead. The customizer is invoked
with five arguments: (objValue, srcValue, key, object, source).
Note: This method mutates object.
Aliases
_.extendWith
Arguments
object (Object): The destination object.sources (…Object): The source objects.[customizer] (Function): The function to customize assigned values.
Returns
(Object): Returns object.
Example
function customizer(objValue, srcValue) {
return _.isUndefined(objValue) ? srcValue : objValue;
}
var defaults = _.partialRight(_.assignInWith, customizer);
defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// → { 'a': 1, 'b': 2 }
_.assignWith(object, sources, [customizer])
# Ⓢ Ⓣ Ⓝ
This method is like _.assign except that it accepts customizer which
is invoked to produce the assigned values. If customizer returns undefined
assignment is handled by the method instead. The customizer is invoked
with five arguments: (objValue, srcValue, key, object, source).
Note: This method mutates object.
Arguments
object (Object): The destination object.sources (…Object): The source objects.[customizer] (Function): The function to customize assigned values.
Returns
(Object): Returns object.
Example
function customizer(objValue, srcValue) {
return _.isUndefined(objValue) ? srcValue : objValue;
}
var defaults = _.partialRight(_.assignWith, customizer);
defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// → { 'a': 1, 'b': 2 }
_.at(object, [paths])
# Ⓢ Ⓣ Ⓝ
Creates an array of values corresponding to paths of object.
Arguments
object (Object): The object to iterate over.[paths] (…(string|string[]): The property paths of elements to pick, specified individually or in arrays.
Returns
(Array): Returns the new array of picked elements.
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };
_.at(object, ['a[0].b.c', 'a[1]']);
// → [3, 4]
_.at(['a', 'b', 'c'], 0, 2);
// → ['a', 'c']
_.create(prototype, [properties])
# Ⓢ Ⓣ Ⓝ
Creates an object that inherits from the prototype object. If a properties
object is given its own enumerable properties are assigned to the created object.
Arguments
prototype (Object): The object to inherit from.[properties] (Object): The properties to assign to the object.
Returns
(Object): Returns the new object.
Example
function Shape() {
this.x = 0;
this.y = 0;
}
function Circle() {
Shape.call(this);
}
Circle.prototype = _.create(Shape.prototype, {
'constructor': Circle
});
var circle = new Circle;
circle instanceof Circle;
// → true
circle instanceof Shape;
// → true
_.defaults(object, [sources])
# Ⓢ Ⓣ Ⓝ
Assigns own and inherited enumerable properties of source objects to the
destination object for all destination properties that resolve to undefined.
Source objects are applied from left to right. Once a property is set,
additional values of the same property are ignored.
Note: This method mutates object.
Arguments
object (Object): The destination object.[sources] (…Object): The source objects.
Returns
(Object): Returns object.
Example
_.defaults({ 'user': 'barney' }, { 'age': 36 }, { 'user': 'fred' });
// → { 'user': 'barney', 'age': 36 }
_.defaultsDeep(object, [sources])
# Ⓢ Ⓣ Ⓝ
This method is like _.defaults except that it recursively assigns
default properties.
Note: This method mutates object.
Arguments
object (Object): The destination object.[sources] (…Object): The source objects.
Returns
(Object): Returns object.
Example
_.defaultsDeep({ 'user': { 'name': 'barney' } }, { 'user': { 'name': 'fred', 'age': 36 } });
// → { 'user': { 'name': 'barney', 'age': 36 } }
_.findKey(object, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.find except that it returns the key of the first
element predicate returns truthy for instead of the element itself.
Arguments
object (Object): The object to search.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(string|undefined): Returns the key of the matched element, else undefined.
Example
var users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 1, 'active': true }
};
_.findKey(users, function(o) { return o.age < 40; });
// → 'barney' (iteration order is not guaranteed)
// The `_.matches` iteratee shorthand.
_.findKey(users, { 'age': 1, 'active': true });
// → 'pebbles'
// The `_.matchesProperty` iteratee shorthand.
_.findKey(users, ['active', false]);
// → 'fred'
// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// → 'barney'
_.findLastKey(object, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.findKey except that it iterates over elements of
a collection in the opposite order.
Arguments
object (Object): The object to search.[predicate=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(string|undefined): Returns the key of the matched element, else undefined.
Example
var users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 1, 'active': true }
};
_.findLastKey(users, function(o) { return o.age < 40; });
// → returns 'pebbles' assuming `_.findKey` returns 'barney'
// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// → 'barney'
// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// → 'fred'
// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// → 'pebbles'
_.forIn(object, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Iterates over own and inherited enumerable properties of an object invoking
iteratee for each property. The iteratee is invoked with three arguments:
(value, key, object). Iteratee functions may exit iteration early by explicitly
returning false.
Arguments
object (Object): The object to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.
Returns
(Object): Returns object.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forIn(new Foo, function(value, key) {
console.log(key);
});
// → logs 'a', 'b', then 'c' (iteration order is not guaranteed)
_.forInRight(object, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.forIn except that it iterates over properties of
object in the opposite order.
Arguments
object (Object): The object to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.
Returns
(Object): Returns object.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forInRight(new Foo, function(value, key) {
console.log(key);
});
// → logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'
_.forOwn(object, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Iterates over own enumerable properties of an object invoking iteratee
for each property. The iteratee is invoked with three arguments:
(value, key, object). Iteratee functions may exit iteration early by
explicitly returning false.
Arguments
object (Object): The object to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.
Returns
(Object): Returns object.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forOwn(new Foo, function(value, key) {
console.log(key);
});
// → logs 'a' then 'b' (iteration order is not guaranteed)
_.forOwnRight(object, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.forOwn except that it iterates over properties of
object in the opposite order.
Arguments
object (Object): The object to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.
Returns
(Object): Returns object.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forOwnRight(new Foo, function(value, key) {
console.log(key);
});
// → logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'
_.functions(object)
# Ⓢ Ⓣ Ⓝ
Creates an array of function property names from own enumerable properties
of object.
Arguments
object (Object): The object to inspect.
Returns
(Array): Returns the new array of property names.
Example
function Foo() {
this.a = _.constant('a');
this.b = _.constant('b');
}
Foo.prototype.c = _.constant('c');
_.functions(new Foo);
// → ['a', 'b']
_.functionsIn(object)
# Ⓢ Ⓣ Ⓝ
Creates an array of function property names from own and inherited
enumerable properties of object.
Arguments
object (Object): The object to inspect.
Returns
(Array): Returns the new array of property names.
Example
function Foo() {
this.a = _.constant('a');
this.b = _.constant('b');
}
Foo.prototype.c = _.constant('c');
_.functionsIn(new Foo);
// → ['a', 'b', 'c']
_.get(object, path, [defaultValue])
# Ⓢ Ⓣ Ⓝ
Gets the value at path of object. If the resolved value is
undefined the defaultValue is used in its place.
Arguments
object (Object): The object to query.path (Array|string): The path of the property to get.[defaultValue] (*): The value returned if the resolved value is undefined.
Returns
(*): Returns the resolved value.
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.get(object, 'a[0].b.c');
// → 3
_.get(object, ['a', '0', 'b', 'c']);
// → 3
_.get(object, 'a.b.c', 'default');
// → 'default'
_.has(object, path)
# Ⓢ Ⓣ Ⓝ
Checks if path is a direct property of object.
Arguments
object (Object): The object to query.path (Array|string): The path to check.
Returns
(boolean): Returns true if path exists, else false.
Example
var object = { 'a': { 'b': { 'c': 3 } } };
var other = _.create({ 'a': _.create({ 'b': _.create({ 'c': 3 }) }) });
_.has(object, 'a');
// → true
_.has(object, 'a.b.c');
// → true
_.has(object, ['a', 'b', 'c']);
// → true
_.has(other, 'a');
// → false
_.hasIn(object, path)
# Ⓢ Ⓣ Ⓝ
Checks if path is a direct or inherited property of object.
Arguments
object (Object): The object to query.path (Array|string): The path to check.
Returns
(boolean): Returns true if path exists, else false.
Example
var object = _.create({ 'a': _.create({ 'b': _.create({ 'c': 3 }) }) });
_.hasIn(object, 'a');
// → true
_.hasIn(object, 'a.b.c');
// → true
_.hasIn(object, ['a', 'b', 'c']);
// → true
_.hasIn(object, 'b');
// → false
_.invert(object)
# Ⓢ Ⓣ Ⓝ
Creates an object composed of the inverted keys and values of object.
If object contains duplicate values, subsequent values overwrite property
assignments of previous values.
Arguments
object (Object): The object to invert.
Returns
(Object): Returns the new inverted object.
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };
_.invert(object);
// → { '1': 'c', '2': 'b' }
_.invertBy(object, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
This method is like _.invert except that the inverted object is generated
from the results of running each element of object through iteratee.
The corresponding inverted value of each inverted key is an array of keys
responsible for generating the inverted value. The iteratee is invoked
with one argument: (value).
Arguments
object (Object): The object to invert.[iteratee=_.identity] (Function|Object|string): The iteratee invoked per element.
Returns
(Object): Returns the new inverted object.
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };
_.invertBy(object);
// → { '1': ['a', 'c'], '2': ['b'] }
_.invertBy(object, function(value) {
return 'group' + value;
});
// → { 'group1': ['a', 'c'], 'group2': ['b'] }
_.invoke(object, path, [args])
# Ⓢ Ⓣ Ⓝ
Invokes the method at path of object.
Arguments
object (Object): The object to query.path (Array|string): The path of the method to invoke.[args] (…*): The arguments to invoke the method with.
Returns
(*): Returns the result of the invoked method.
Example
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };
_.invoke(object, 'a[0].b.c.slice', 1, 3);
// → [2, 3]
_.keys(object)
# Ⓢ Ⓣ Ⓝ
Creates an array of the own enumerable property names of object.
Note: Non-object values are coerced to objects. See the
ES spec
for more details.
Arguments
object (Object): The object to query.
Returns
(Array): Returns the array of property names.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.keys(new Foo);
// → ['a', 'b'] (iteration order is not guaranteed)
_.keys('hi');
// → ['0', '1']
_.keysIn(object)
# Ⓢ Ⓣ Ⓝ
Creates an array of the own and inherited enumerable property names of object.
Note: Non-object values are coerced to objects.
Arguments
object (Object): The object to query.
Returns
(Array): Returns the array of property names.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.keysIn(new Foo);
// → ['a', 'b', 'c'] (iteration order is not guaranteed)
_.mapKeys(object, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
The opposite of _.mapValues; this method creates an object with the
same values as object and keys generated by running each own enumerable
property of object through iteratee. The iteratee is invoked with
three arguments: (value, key, object).
Arguments
object (Object): The object to iterate over.[iteratee=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Object): Returns the new mapped object.
Example
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
return key + value;
});
// → { 'a1': 1, 'b2': 2 }
_.mapValues(object, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates an object with the same keys as object and values generated by
running each own enumerable property of object through iteratee. The
iteratee is invoked with three arguments: (value, key, object).
Arguments
object (Object): The object to iterate over.[iteratee=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Object): Returns the new mapped object.
Example
var users = {
'fred': { 'user': 'fred', 'age': 40 },
'pebbles': { 'user': 'pebbles', 'age': 1 }
};
_.mapValues(users, function(o) { return o.age; });
// → { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
// The `_.property` iteratee shorthand.
_.mapValues(users, 'age');
// → { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
_.merge(object, [sources])
# Ⓢ Ⓣ Ⓝ
This method is like _.assign except that it recursively merges own and
inherited enumerable properties of source objects into the destination
object. Source properties that resolve to undefined are skipped if a
destination value exists. Array and plain object properties are merged
recursively.Other objects and value types are overridden by assignment.
Source objects are applied from left to right. Subsequent sources
overwrite property assignments of previous sources.
Note: This method mutates object.
Arguments
object (Object): The destination object.[sources] (…Object): The source objects.
Returns
(Object): Returns object.
Example
var users = {
'data': [{ 'user': 'barney' }, { 'user': 'fred' }]
};
var ages = {
'data': [{ 'age': 36 }, { 'age': 40 }]
};
_.merge(users, ages);
// → { 'data': [{ 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }] }
_.mergeWith(object, sources, customizer)
# Ⓢ Ⓣ Ⓝ
This method is like _.merge except that it accepts customizer which
is invoked to produce the merged values of the destination and source
properties. If customizer returns undefined merging is handled by the
method instead. The customizer is invoked with seven arguments:
(objValue, srcValue, key, object, source, stack).
Note: This method mutates object.
Arguments
object (Object): The destination object.sources (…Object): The source objects.customizer (Function): The function to customize assigned values.
Returns
(Object): Returns object.
Example
function customizer(objValue, srcValue) {
if (_.isArray(objValue)) {
return objValue.concat(srcValue);
}
}
var object = {
'fruits': ['apple'],
'vegetables': ['beet']
};
var other = {
'fruits': ['banana'],
'vegetables': ['carrot']
};
_.mergeWith(object, other, customizer);
// → { 'fruits': ['apple', 'banana'], 'vegetables': ['beet', 'carrot'] }
_.omit(object, [props])
# Ⓢ Ⓣ Ⓝ
The opposite of _.pick; this method creates an object composed of the
own and inherited enumerable properties of object that are not omitted.
Arguments
object (Object): The source object.[props] (…(string|string[]): The property names to omit, specified individually or in arrays.
Returns
(Object): Returns the new object.
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.omit(object, ['a', 'c']);
// → { 'b': '2' }
_.omitBy(object, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
The opposite of _.pickBy; this method creates an object composed of
the own and inherited enumerable properties of object that predicate
doesn’t return truthy for. The predicate is invoked with two arguments:
(value, key).
Arguments
object (Object): The source object.[predicate=_.identity] (Function|Object|string): The function invoked per property.
Returns
(Object): Returns the new object.
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.omitBy(object, _.isNumber);
// → { 'b': '2' }
_.pick(object, [props])
# Ⓢ Ⓣ Ⓝ
Creates an object composed of the picked object properties.
Arguments
object (Object): The source object.[props] (…(string|string[]): The property names to pick, specified individually or in arrays.
Returns
(Object): Returns the new object.
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.pick(object, ['a', 'c']);
// → { 'a': 1, 'c': 3 }
_.pickBy(object, [predicate=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates an object composed of the object properties predicate returns
truthy for. The predicate is invoked with two arguments: (value, key).
Arguments
object (Object): The source object.[predicate=_.identity] (Function|Object|string): The function invoked per property.
Returns
(Object): Returns the new object.
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.pickBy(object, _.isNumber);
// → { 'a': 1, 'c': 3 }
_.result(object, path, [defaultValue])
# Ⓢ Ⓣ Ⓝ
This method is like _.get except that if the resolved value is a function
it’s invoked with the this binding of its parent object and its result
is returned.
Arguments
object (Object): The object to query.path (Array|string): The path of the property to resolve.[defaultValue] (*): The value returned if the resolved value is undefined.
Returns
(*): Returns the resolved value.
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };
_.result(object, 'a[0].b.c1');
// → 3
_.result(object, 'a[0].b.c2');
// → 4
_.result(object, 'a[0].b.c3', 'default');
// → 'default'
_.result(object, 'a[0].b.c3', _.constant('default'));
// → 'default'
_.set(object, path, value)
# Ⓢ Ⓣ Ⓝ
Sets the value at path of object. If a portion of path doesn’t exist
it’s created. Arrays are created for missing index properties while objects
are created for all other missing properties. Use _.setWith to customize
path creation.
Note: This method mutates object.
Arguments
object (Object): The object to modify.path (Array|string): The path of the property to set.value (*): The value to set.
Returns
(Object): Returns object.
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.set(object, 'a[0].b.c', 4);
console.log(object.a[0].b.c);
// → 4
_.set(object, 'x[0].y.z', 5);
console.log(object.x[0].y.z);
// → 5
_.setWith(object, path, value, [customizer])
# Ⓢ Ⓣ Ⓝ
This method is like _.set except that it accepts customizer which is
invoked to produce the objects of path. If customizer returns undefined
path creation is handled by the method instead. The customizer is invoked
with three arguments: (nsValue, key, nsObject).
Note: This method mutates object.
Arguments
object (Object): The object to modify.path (Array|string): The path of the property to set.value (*): The value to set.[customizer] (Function): The function to customize assigned values.
Returns
(Object): Returns object.
Example
var object = {};
_.setWith(object, '[0][1]', 'a', Object);
// → { '0': { '1': 'a' } }
_.toPairs(object)
# Ⓢ Ⓣ Ⓝ
Creates an array of own enumerable key-value pairs for object which
can be consumed by _.fromPairs.
Arguments
object (Object): The object to query.
Returns
(Array): Returns the new array of key-value pairs.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.toPairs(new Foo);
// → [['a', 1], ['b', 2]] (iteration order is not guaranteed)
_.toPairsIn(object)
# Ⓢ Ⓣ Ⓝ
Creates an array of own and inherited enumerable key-value pairs for
object which can be consumed by _.fromPairs.
Arguments
object (Object): The object to query.
Returns
(Array): Returns the new array of key-value pairs.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.toPairsIn(new Foo);
// → [['a', 1], ['b', 2], ['c', 1]] (iteration order is not guaranteed)
_.transform(object, [iteratee=_.identity], [accumulator])
# Ⓢ Ⓣ Ⓝ
An alternative to _.reduce; this method transforms object to a new
accumulator object which is the result of running each of its own enumerable
properties through iteratee, with each invocation potentially mutating
the accumulator object. The iteratee is invoked with four arguments:
(accumulator, value, key, object). Iteratee functions may exit iteration
early by explicitly returning false.
Arguments
object (Array|Object): The object to iterate over.[iteratee=_.identity] (Function): The function invoked per iteration.[accumulator] (*): The custom accumulator value.
Returns
(*): Returns the accumulated value.
Example
_.transform([2, 3, 4], function(result, n) {
result.push(n *= n);
return n % 2 == 0;
}, []);
// → [4, 9]
_.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
(result[value] || (result[value] = [])).push(key);
}, {});
// → { '1': ['a', 'c'], '2': ['b'] }
_.unset(object, path)
# Ⓢ Ⓣ Ⓝ
Removes the property at path of object.
Note: This method mutates object.
Arguments
object (Object): The object to modify.path (Array|string): The path of the property to unset.
Returns
(boolean): Returns true if the property is deleted, else false.
Example
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset(object, 'a[0].b.c');
// → true
console.log(object);
// → { 'a': [{ 'b': {} }] };
_.unset(object, 'a[0].b.c');
// → true
console.log(object);
// → { 'a': [{ 'b': {} }] };
_.update(object, path, updater)
# Ⓢ Ⓣ Ⓝ
This method is like _.set except that accepts updater to produce the
value to set. Use _.updateWith to customize path creation. The updater
is invoked with one argument: (value).
Note: This method mutates object.
Arguments
object (Object): The object to modify.path (Array|string): The path of the property to set.updater (Function): The function to produce the updated value.
Returns
(Object): Returns object.
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.update(object, 'a[0].b.c', function(n) { return n * n; });
console.log(object.a[0].b.c);
// → 9
_.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
console.log(object.x[0].y.z);
// → 0
_.updateWith(object, path, updater, [customizer])
# Ⓢ Ⓣ Ⓝ
This method is like _.update except that it accepts customizer which is
invoked to produce the objects of path. If customizer returns undefined
path creation is handled by the method instead. The customizer is invoked
with three arguments: (nsValue, key, nsObject).
Note: This method mutates object.
Arguments
object (Object): The object to modify.path (Array|string): The path of the property to set.updater (Function): The function to produce the updated value.[customizer] (Function): The function to customize assigned values.
Returns
(Object): Returns object.
Example
var object = {};
_.updateWith(object, '[0][1]', _.constant('a'), Object);
// → { '0': { '1': 'a' } }
_.values(object)
# Ⓢ Ⓣ Ⓝ
Creates an array of the own enumerable property values of object.
Note: Non-object values are coerced to objects.
Arguments
object (Object): The object to query.
Returns
(Array): Returns the array of property values.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.values(new Foo);
// → [1, 2] (iteration order is not guaranteed)
_.values('hi');
// → ['h', 'i']
_.valuesIn(object)
# Ⓢ Ⓣ Ⓝ
Creates an array of the own and inherited enumerable property values of object.
Note: Non-object values are coerced to objects.
Arguments
object (Object): The object to query.
Returns
(Array): Returns the array of property values.
Example
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.valuesIn(new Foo);
// → [1, 2, 3] (iteration order is not guaranteed)
“Seq” Methods
_(value)
# Ⓢ Ⓣ
Creates a lodash object which wraps value to enable implicit method
chaining. Methods that operate on and return arrays, collections, and
functions can be chained together. Methods that retrieve a single value or
may return a primitive value will automatically end the chain sequence and
return the unwrapped value. Otherwise, the value must be unwrapped with
_#value.
Explicit chaining, which must be unwrapped with _#value in all cases,
may be enabled using _.chain.
The execution of chained methods is lazy, that is, it’s deferred until
_#value is implicitly or explicitly called.
Lazy evaluation allows several methods to support shortcut fusion. Shortcut
fusion is an optimization to merge iteratee calls; this avoids the creation
of intermediate arrays and can greatly reduce the number of iteratee executions.
Sections of a chain sequence qualify for shortcut fusion if the section is
applied to an array of at least two hundred elements and any iteratees
accept only one argument. The heuristic for whether a section qualifies
for shortcut fusion is subject to change.
Chaining is supported in custom builds as long as the _#value method is
directly or indirectly included in the build.
In addition to lodash methods, wrappers have Array and String methods.
The wrapper Array methods are:
concat, join, pop, push, shift, sort, splice, and unshift
The wrapper String methods are:
replace and split
The wrapper methods that support shortcut fusion are:
at, compact, drop, dropRight, dropWhile, filter, find,
findLast, head, initial, last, map, reject, reverse, slice,
tail, take, takeRight, takeRightWhile, takeWhile, and toArray
The chainable wrapper methods are:
after, ary, assign, assignIn, assignInWith, assignWith, at,
before, bind, bindAll, bindKey, castArray, chain, chunk,
commit, compact, concat, conforms, constant, countBy, create,
curry, debounce, defaults, defaultsDeep, defer, delay,
difference, differenceBy, differenceWith, drop, dropRight,
dropRightWhile, dropWhile, extend, extendWith, fill, filter,
flatten, flattenDeep, flattenDepth, flip, flow, flowRight,
fromPairs, functions, functionsIn, groupBy, initial, intersection,
intersectionBy, intersectionWith, invert, invertBy, invokeMap,
iteratee, keyBy, keys, keysIn, map, mapKeys, mapValues,
matches, matchesProperty, memoize, merge, mergeWith, method,
methodOf, mixin, negate, nthArg, omit, omitBy, once, orderBy,
over, overArgs, overEvery, overSome, partial, partialRight,
partition, pick, pickBy, plant, property, propertyOf, pull,
pullAll, pullAllBy, pullAllWith, pullAt, push, range,
rangeRight, rearg, reject, remove, rest, reverse, sampleSize,
set, setWith, shuffle, slice, sort, sortBy, splice, spread,
tail, take, takeRight, takeRightWhile, takeWhile, tap, throttle,
thru, toArray, toPairs, toPairsIn, toPath, toPlainObject,
transform, unary, union, unionBy, unionWith, uniq, uniqBy,
uniqWith, unset, unshift, unzip, unzipWith, update, values,
valuesIn, without, wrap, xor, xorBy, xorWith, zip, zipObject,
zipObjectDeep, and zipWith
The wrapper methods that are not chainable by default are:
add, attempt, camelCase, capitalize, ceil, clamp, clone,
cloneDeep, cloneDeepWith, cloneWith, deburr, each, eachRight,
endsWith, eq, escape, escapeRegExp, every, find, findIndex,
findKey, findLast, findLastIndex, findLastKey, first, floor,
forEach, forEachRight, forIn, forInRight, forOwn, forOwnRight,
get, gt, gte, has, hasIn, head, identity, includes,
indexOf, inRange, invoke, isArguments, isArray, isArrayBuffer,
isArrayLike, isArrayLikeObject, isBoolean, isBuffer, isDate,
isElement, isEmpty, isEqual, isEqualWith, isError, isFinite,
isFunction, isInteger, isLength, isMap, isMatch, isMatchWith,
isNaN, isNative, isNil, isNull, isNumber, isObject, isObjectLike,
isPlainObject, isRegExp, isSafeInteger, isSet, isString,
isUndefined, isTypedArray, isWeakMap, isWeakSet, join, kebabCase,
last, lastIndexOf, lowerCase, lowerFirst, lt, lte, max,
maxBy, mean, min, minBy, noConflict, noop, now, pad,
padEnd, padStart, parseInt, pop, random, reduce, reduceRight,
repeat, result, round, runInContext, sample, shift, size,
snakeCase, some, sortedIndex, sortedIndexBy, sortedLastIndex,
sortedLastIndexBy, startCase, startsWith, subtract, sum, sumBy,
template, times, toInteger, toJSON, toLength, toLower,
toNumber, toSafeInteger, toString, toUpper, trim, trimEnd,
trimStart, truncate, unescape, uniqueId, upperCase, upperFirst,
value, and words
Arguments
value (*): The value to wrap in a lodash instance.
Returns
(Object): Returns the new lodash wrapper instance.
Example
function square(n) {
return n * n;
}
var wrapped = _([1, 2, 3]);
// Returns an unwrapped value.
wrapped.reduce(_.add);
// → 6
// Returns a wrapped value.
var squares = wrapped.map(square);
_.isArray(squares);
// → false
_.isArray(squares.value());
// → true
_.chain(value)
# Ⓢ Ⓣ
Creates a lodash object that wraps value with explicit method chaining enabled.
The result of such method chaining must be unwrapped with _#value.
Arguments
value (*): The value to wrap.
Returns
(Object): Returns the new lodash wrapper instance.
Example
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 },
{ 'user': 'pebbles', 'age': 1 }
];
var youngest = _
.chain(users)
.sortBy('age')
.map(function(o) {
return o.user + ' is ' + o.age;
})
.head()
.value();
// → 'pebbles is 1'
_.tap(value, interceptor)
# Ⓢ Ⓣ
This method invokes interceptor and returns value. The interceptor
is invoked with one argument; (value). The purpose of this method is to
"tap into" a method chain in order to modify intermediate results.
Arguments
value (*): The value to provide to interceptor.interceptor (Function): The function to invoke.
Returns
(*): Returns value.
Example
_([1, 2, 3])
.tap(function(array) {
// Mutate input array.
array.pop();
})
.reverse()
.value();
// → [2, 1]
_.thru(value, interceptor)
# Ⓢ Ⓣ
This method is like _.tap except that it returns the result of interceptor.
The purpose of this method is to "pass thru" values replacing intermediate
results in a method chain.
Arguments
value (*): The value to provide to interceptor.interceptor (Function): The function to invoke.
Returns
(*): Returns the result of interceptor.
Example
_(' abc ')
.chain()
.trim()
.thru(function(value) {
return [value];
})
.value();
// → ['abc']
_.prototype[Symbol.iterator]()
# Ⓢ Ⓣ
Enables the wrapper to be iterable.
Returns
(Object): Returns the wrapper object.
Example
var wrapped = _([1, 2]);
wrapped[Symbol.iterator]() === wrapped;
// → true
Array.from(wrapped);
// → [1, 2]
_.prototype.at([paths])
# Ⓢ Ⓣ
This method is the wrapper version of _.at.
Arguments
[paths] (…(string|string[]): The property paths of elements to pick, specified individually or in arrays.
Returns
(Object): Returns the new lodash wrapper instance.
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };
_(object).at(['a[0].b.c', 'a[1]']).value();
// → [3, 4]
_(['a', 'b', 'c']).at(0, 2).value();
// → ['a', 'c']
_.prototype.chain()
# Ⓢ Ⓣ
Enables explicit method chaining on the wrapper object.
Returns
(Object): Returns the new lodash wrapper instance.
Example
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 }
];
// A sequence without explicit chaining.
_(users).head();
// → { 'user': 'barney', 'age': 36 }
// A sequence with explicit chaining.
_(users)
.chain()
.head()
.pick('user')
.value();
// → { 'user': 'barney' }
_.prototype.commit()
# Ⓢ Ⓣ
Executes the chained sequence and returns the wrapped result.
Returns
(Object): Returns the new lodash wrapper instance.
Example
var array = [1, 2];
var wrapped = _(array).push(3);
console.log(array);
// → [1, 2]
wrapped = wrapped.commit();
console.log(array);
// → [1, 2, 3]
wrapped.last();
// → 3
console.log(array);
// → [1, 2, 3]
_.prototype.flatMap([iteratee=_.identity])
# Ⓢ Ⓣ
This method is the wrapper version of _.flatMap.
Arguments
[iteratee=_.identity] (Function|Object|string): The function invoked per iteration.
Returns
(Object): Returns the new lodash wrapper instance.
Example
function duplicate(n) {
return [n, n];
}
_([1, 2]).flatMap(duplicate).value();
// → [1, 1, 2, 2]
_.prototype.next()
# Ⓢ Ⓣ
Gets the next value on a wrapped object following the
iterator protocol.
Returns
(Object): Returns the next iterator value.
Example
var wrapped = _([1, 2]);
wrapped.next();
// → { 'done': false, 'value': 1 }
wrapped.next();
// → { 'done': false, 'value': 2 }
wrapped.next();
// → { 'done': true, 'value': undefined }
_.prototype.plant(value)
# Ⓢ Ⓣ
Creates a clone of the chained sequence planting value as the wrapped value.
Arguments
value (*): The value to plant.
Returns
(Object): Returns the new lodash wrapper instance.
Example
function square(n) {
return n * n;
}
var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);
other.value();
// → [9, 16]
wrapped.value();
// → [1, 4]
_.prototype.reverse()
# Ⓢ Ⓣ
This method is the wrapper version of _.reverse.
Note: This method mutates the wrapped array.
Returns
(Object): Returns the new lodash wrapper instance.
Example
var array = [1, 2, 3];
_(array).reverse().value()
// → [3, 2, 1]
console.log(array);
// → [3, 2, 1]
_.prototype.value()
# Ⓢ Ⓣ
Executes the chained sequence to extract the unwrapped value.
Aliases
_.prototype.toJSON, _.prototype.valueOf
Returns
(*): Returns the resolved unwrapped value.
Example
_([1, 2, 3]).value();
// → [1, 2, 3]
“String” Methods
_.camelCase([string=''])
# Ⓢ Ⓣ Ⓝ
Converts string to camel case.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the camel cased string.
Example
_.camelCase('Foo Bar');
// → 'fooBar'
_.camelCase('--foo-bar');
// → 'fooBar'
_.camelCase('__foo_bar__');
// → 'fooBar'
_.capitalize([string=''])
# Ⓢ Ⓣ Ⓝ
Converts the first character of string to upper case and the remaining
to lower case.
Arguments
[string=''] (string): The string to capitalize.
Returns
(string): Returns the capitalized string.
Example
_.capitalize('FRED');
// → 'Fred'
_.endsWith([string=''], [target], [position=string.length])
# Ⓢ Ⓣ Ⓝ
Checks if string ends with the given target string.
Arguments
[string=''] (string): The string to search.[target] (string): The string to search for.[position=string.length] (number): The position to search from.
Returns
(boolean): Returns true if string ends with target, else false.
Example
_.endsWith('abc', 'c');
// → true
_.endsWith('abc', 'b');
// → false
_.endsWith('abc', 'b', 2);
// → true
_.escape([string=''])
# Ⓢ Ⓣ Ⓝ
Converts the characters "&", "<", ">", '"', "'", and "`" in string to
their corresponding HTML entities.
Note: No other characters are escaped. To escape additional
characters use a third-party library like he.
Though the ">" character is escaped for symmetry, characters like
">" and "/" don’t need escaping in HTML and have no special meaning
unless they're part of a tag or unquoted attribute value.
See Mathias Bynens’s article
(under "semi-related fun fact") for more details.
Backticks are escaped because in IE < 9, they can break out of
attribute values or HTML comments. See #59,
#102, #108, and
#133 of the HTML5 Security Cheatsheet
for more details.
When working with HTML you should always quote attribute values
to reduce XSS vectors.
Arguments
[string=''] (string): The string to escape.
Returns
(string): Returns the escaped string.
Example
_.escape('fred, barney, & pebbles');
// → 'fred, barney, & pebbles'
_.escapeRegExp([string=''])
# Ⓢ Ⓣ Ⓝ
Escapes the RegExp special characters "^", "$", "\", ".", "*", "+",
"?", "(", ")", "[", "]", "{", "}", and "|" in string.
Arguments
[string=''] (string): The string to escape.
Returns
(string): Returns the escaped string.
Example
_.escapeRegExp('[lodash](https://lodash.com/)');
// → '\[lodash\]\(https://lodash\.com/\)'
_.kebabCase([string=''])
# Ⓢ Ⓣ Ⓝ
Converts string to kebab case.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the kebab cased string.
Example
_.kebabCase('Foo Bar');
// → 'foo-bar'
_.kebabCase('fooBar');
// → 'foo-bar'
_.kebabCase('__foo_bar__');
// → 'foo-bar'
_.lowerCase([string=''])
# Ⓢ Ⓣ Ⓝ
Converts string, as space separated words, to lower case.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the lower cased string.
Example
_.lowerCase('--Foo-Bar');
// → 'foo bar'
_.lowerCase('fooBar');
// → 'foo bar'
_.lowerCase('__FOO_BAR__');
// → 'foo bar'
_.lowerFirst([string=''])
# Ⓢ Ⓣ Ⓝ
Converts the first character of string to lower case.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the converted string.
Example
_.lowerFirst('Fred');
// → 'fred'
_.lowerFirst('FRED');
// → 'fRED'
_.pad([string=''], [length=0], [chars=' '])
# Ⓢ Ⓣ Ⓝ
Pads string on the left and right sides if it’s shorter than length.
Padding characters are truncated if they can’t be evenly divided by length.
Arguments
[string=''] (string): The string to pad.[length=0] (number): The padding length.[chars=' '] (string): The string used as padding.
Returns
(string): Returns the padded string.
Example
_.pad('abc', 8);
// → ' abc '
_.pad('abc', 8, '_-');
// → '_-abc_-_'
_.pad('abc', 3);
// → 'abc'
_.padEnd([string=''], [length=0], [chars=' '])
# Ⓢ Ⓣ Ⓝ
Pads string on the right side if it’s shorter than length. Padding
characters are truncated if they exceed length.
Arguments
[string=''] (string): The string to pad.[length=0] (number): The padding length.[chars=' '] (string): The string used as padding.
Returns
(string): Returns the padded string.
Example
_.padEnd('abc', 6);
// → 'abc '
_.padEnd('abc', 6, '_-');
// → 'abc_-_'
_.padEnd('abc', 3);
// → 'abc'
_.padStart([string=''], [length=0], [chars=' '])
# Ⓢ Ⓣ Ⓝ
Pads string on the left side if it’s shorter than length. Padding
characters are truncated if they exceed length.
Arguments
[string=''] (string): The string to pad.[length=0] (number): The padding length.[chars=' '] (string): The string used as padding.
Returns
(string): Returns the padded string.
Example
_.padStart('abc', 6);
// → ' abc'
_.padStart('abc', 6, '_-');
// → '_-_abc'
_.padStart('abc', 3);
// → 'abc'
_.parseInt(string, [radix=10])
# Ⓢ Ⓣ Ⓝ
Converts string to an integer of the specified radix. If radix is
undefined or 0, a radix of 10 is used unless value is a hexadecimal,
in which case a radix of 16 is used.
Note: This method aligns with the ES5 implementation
of parseInt.
Arguments
string (string): The string to convert.[radix=10] (number): The radix to interpret value by.
Returns
(number): Returns the converted integer.
Example
_.parseInt('08');
// → 8
_.map(['6', '08', '10'], _.parseInt);
// → [6, 8, 10]
_.repeat([string=''], [n=0])
# Ⓢ Ⓣ Ⓝ
Repeats the given string n times.
Arguments
[string=''] (string): The string to repeat.[n=0] (number): The number of times to repeat the string.
Returns
(string): Returns the repeated string.
Example
_.repeat('*', 3);
// → '***'
_.repeat('abc', 2);
// → 'abcabc'
_.repeat('abc', 0);
// → ''
_.replace([string=''], pattern, replacement)
# Ⓢ Ⓣ Ⓝ
Replaces matches for pattern in string with replacement.
Note: This method is based on String#replace.
Arguments
[string=''] (string): The string to modify.pattern (RegExp|string): The pattern to replace.replacement (Function|string): The match replacement.
Returns
(string): Returns the modified string.
Example
_.replace('Hi Fred', 'Fred', 'Barney');
// → 'Hi Barney'
_.snakeCase([string=''])
# Ⓢ Ⓣ Ⓝ
Converts string to snake case.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the snake cased string.
Example
_.snakeCase('Foo Bar');
// → 'foo_bar'
_.snakeCase('fooBar');
// → 'foo_bar'
_.snakeCase('--foo-bar');
// → 'foo_bar'
_.split([string=''], separator, [limit])
# Ⓢ Ⓣ Ⓝ
Splits string by separator.
Note: This method is based on String#split.
Arguments
[string=''] (string): The string to split.separator (RegExp|string): The separator pattern to split by.[limit] (number): The length to truncate results to.
Returns
(Array): Returns the new array of string segments.
Example
_.split('a-b-c', '-', 2);
// → ['a', 'b']
_.startCase([string=''])
# Ⓢ Ⓣ Ⓝ
Converts string to start case.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the start cased string.
Example
_.startCase('--foo-bar');
// → 'Foo Bar'
_.startCase('fooBar');
// → 'Foo Bar'
_.startCase('__foo_bar__');
// → 'Foo Bar'
_.startsWith([string=''], [target], [position=0])
# Ⓢ Ⓣ Ⓝ
Checks if string starts with the given target string.
Arguments
[string=''] (string): The string to search.[target] (string): The string to search for.[position=0] (number): The position to search from.
Returns
(boolean): Returns true if string starts with target, else false.
Example
_.startsWith('abc', 'a');
// → true
_.startsWith('abc', 'b');
// → false
_.startsWith('abc', 'b', 1);
// → true
_.template([string=''], [options])
# Ⓢ Ⓣ Ⓝ
Creates a compiled template function that can interpolate data properties
in "interpolate" delimiters, HTML-escape interpolated data properties in
"escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data
properties may be accessed as free variables in the template. If a setting
object is given it takes precedence over _.templateSettings values.
Note: In the development build _.template utilizes
sourceURLs
for easier debugging.
For more information on precompiling templates see
lodash’s custom builds documentation.
For more information on Chrome extension sandboxes see
Chrome’s extensions documentation.
Arguments
[string=''] (string): The template string.[options] (Object): The options object.[options.escape] (RegExp): The HTML "escape" delimiter.[options.evaluate] (RegExp): The "evaluate" delimiter.[options.imports] (Object): An object to import into the template as free variables.[options.interpolate] (RegExp): The "interpolate" delimiter.[options.sourceURL] (string): The sourceURL of the template’s compiled source.[options.variable] (string): The data object variable name.
Returns
(Function): Returns the compiled template function.
Example
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// → 'hello fred!'
// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// → '<b><script></b>'
// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// → '<li>fred</li><li>barney</li>'
// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// → 'hello barney!'
// Use the ES delimiter as an alternative to the default "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// → 'hello pebbles!'
// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// → 'hello mustache!'
// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// → '<%- value %>'
// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template(text, { 'imports': { 'jq': jQuery } });
compiled({ 'users': ['fred', 'barney'] });
// → '<li>fred</li><li>barney</li>'
// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' });
compiled(data);
// → find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector
// Use the `variable` option to ensure a with-statement isn’t used in the compiled template.
var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' });
compiled.source;
// → function(data) {
// var __t, __p = '';
// __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
// return __p;
// }
// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(cwd, 'jst.js'), '\
var JST = {\
"main": ' + _.template(mainText).source + '\
};\
');
_.toLower([string=''])
# Ⓢ Ⓣ Ⓝ
Converts string, as a whole, to lower case just like
String#toLowerCase.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the lower cased string.
Example
_.toLower('--Foo-Bar');
// → '--foo-bar'
_.toLower('fooBar');
// → 'foobar'
_.toLower('__FOO_BAR__');
// → '__foo_bar__'
_.toUpper([string=''])
# Ⓢ Ⓣ Ⓝ
Converts string, as a whole, to upper case just like
String#toUpperCase.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the upper cased string.
Example
_.toUpper('--foo-bar');
// → '--FOO-BAR'
_.toUpper('fooBar');
// → 'FOOBAR'
_.toUpper('__foo_bar__');
// → '__FOO_BAR__'
_.trim([string=''], [chars=whitespace])
# Ⓢ Ⓣ Ⓝ
Removes leading and trailing whitespace or specified characters from string.
Arguments
[string=''] (string): The string to trim.[chars=whitespace] (string): The characters to trim.
Returns
(string): Returns the trimmed string.
Example
_.trim(' abc ');
// → 'abc'
_.trim('-_-abc-_-', '_-');
// → 'abc'
_.map([' foo ', ' bar '], _.trim);
// → ['foo', 'bar']
_.trimEnd([string=''], [chars=whitespace])
# Ⓢ Ⓣ Ⓝ
Removes trailing whitespace or specified characters from string.
Arguments
[string=''] (string): The string to trim.[chars=whitespace] (string): The characters to trim.
Returns
(string): Returns the trimmed string.
Example
_.trimEnd(' abc ');
// → ' abc'
_.trimEnd('-_-abc-_-', '_-');
// → '-_-abc'
_.trimStart([string=''], [chars=whitespace])
# Ⓢ Ⓣ Ⓝ
Removes leading whitespace or specified characters from string.
Arguments
[string=''] (string): The string to trim.[chars=whitespace] (string): The characters to trim.
Returns
(string): Returns the trimmed string.
Example
_.trimStart(' abc ');
// → 'abc '
_.trimStart('-_-abc-_-', '_-');
// → 'abc-_-'
_.truncate([string=''], [options=({})], [options.length=30], [options.omission='…'], [options.separator])
# Ⓢ Ⓣ Ⓝ
Truncates string if it’s longer than the given maximum string length.
The last characters of the truncated string are replaced with the omission
string which defaults to "…".
Arguments
[string=''] (string): The string to truncate.[options=({})] (Object): The options object.[options.length=30] (number): The maximum string length.[options.omission='…'] (string): The string to indicate text is omitted.[options.separator] (RegExp|string): The separator pattern to truncate to.
Returns
(string): Returns the truncated string.
Example
_.truncate('hi-diddly-ho there, neighborino');
// → 'hi-diddly-ho there, neighbo…'
_.truncate('hi-diddly-ho there, neighborino', {
'length': 24,
'separator': ' '
});
// → 'hi-diddly-ho there,…'
_.truncate('hi-diddly-ho there, neighborino', {
'length': 24,
'separator': /,? +/
});
// → 'hi-diddly-ho there…'
_.truncate('hi-diddly-ho there, neighborino', {
'omission': ' […]'
});
// → 'hi-diddly-ho there, neig […]'
_.unescape([string=''])
# Ⓢ Ⓣ Ⓝ
The inverse of _.escape; this method converts the HTML entities
&, <, >, ", ', and ` in string to their
corresponding characters.
Note: No other HTML entities are unescaped. To unescape additional HTML
entities use a third-party library like he.
Arguments
[string=''] (string): The string to unescape.
Returns
(string): Returns the unescaped string.
Example
_.unescape('fred, barney, & pebbles');
// → 'fred, barney, & pebbles'
_.upperCase([string=''])
# Ⓢ Ⓣ Ⓝ
Converts string, as space separated words, to upper case.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the upper cased string.
Example
_.upperCase('--foo-bar');
// → 'FOO BAR'
_.upperCase('fooBar');
// → 'FOO BAR'
_.upperCase('__foo_bar__');
// → 'FOO BAR'
_.upperFirst([string=''])
# Ⓢ Ⓣ Ⓝ
Converts the first character of string to upper case.
Arguments
[string=''] (string): The string to convert.
Returns
(string): Returns the converted string.
Example
_.upperFirst('fred');
// → 'Fred'
_.upperFirst('FRED');
// → 'FRED'
_.words([string=''], [pattern])
# Ⓢ Ⓣ Ⓝ
Splits string into an array of its words.
Arguments
[string=''] (string): The string to inspect.[pattern] (RegExp|string): The pattern to match words.
Returns
(Array): Returns the words of string.
Example
_.words('fred, barney, & pebbles');
// → ['fred', 'barney', 'pebbles']
_.words('fred, barney, & pebbles', /[^, ]+/g);
// → ['fred', 'barney', '&', 'pebbles']
“Util” Methods
_.attempt(func)
# Ⓢ Ⓣ Ⓝ
Attempts to invoke func, returning either the result or the caught error
object. Any additional arguments are provided to func when it’s invoked.
Arguments
func (Function): The function to attempt.
Returns
(*): Returns the func result or error object.
Example
// Avoid throwing errors for invalid selectors.
var elements = _.attempt(function(selector) {
return document.querySelectorAll(selector);
}, '>_>');
if (_.isError(elements)) {
elements = [];
}
_.bindAll(object, methodNames)
# Ⓢ Ⓣ Ⓝ
Binds methods of an object to the object itself, overwriting the existing
method.
Note: This method doesn’t set the "length" property of bound functions.
Arguments
object (Object): The object to bind and assign the bound methods to.methodNames (…(string|string[]): The object method names to bind, specified individually or in arrays.
Returns
(Object): Returns object.
Example
var view = {
'label': 'docs',
'onClick': function() {
console.log('clicked ' + this.label);
}
};
_.bindAll(view, 'onClick');
jQuery(element).on('click', view.onClick);
// → logs 'clicked docs' when clicked
_.cond(pairs)
# Ⓢ Ⓣ Ⓝ
Creates a function that iterates over pairs invoking the corresponding
function of the first predicate to return truthy. The predicate-function
pairs are invoked with the this binding and arguments of the created
function.
Arguments
pairs (Array): The predicate-function pairs.
Returns
(Function): Returns the new function.
Example
var func = _.cond([
[_.matches({ 'a': 1 }), _.constant('matches A')],
[_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
[_.constant(true), _.constant('no match')]
]);
func({ 'a': 1, 'b': 2 });
// → 'matches A'
func({ 'a': 0, 'b': 1 });
// → 'matches B'
func({ 'a': '1', 'b': '2' });
// → 'no match'
_.conforms(source)
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes the predicate properties of source with
the corresponding property values of a given object, returning true if
all predicates return truthy, else false.
Arguments
source (Object): The object of property predicates to conform to.
Returns
(Function): Returns the new function.
Example
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 }
];
_.filter(users, _.conforms({ 'age': _.partial(_.gt, _, 38) }));
// → [{ 'user': 'fred', 'age': 40 }]
_.constant(value)
# Ⓢ Ⓣ Ⓝ
Creates a function that returns value.
Arguments
value (*): The value to return from the new function.
Returns
(Function): Returns the new function.
Example
var object = { 'user': 'fred' };
var getter = _.constant(object);
getter() === object;
// → true
_.flow([funcs])
# Ⓢ Ⓣ Ⓝ
Creates a function that returns the result of invoking the given functions
with the this binding of the created function, where each successive
invocation is supplied the return value of the previous.
Arguments
[funcs] (…(Function|Function[]): Functions to invoke.
Returns
(Function): Returns the new function.
Example
function square(n) {
return n * n;
}
var addSquare = _.flow(_.add, square);
addSquare(1, 2);
// → 9
_.flowRight([funcs])
# Ⓢ Ⓣ Ⓝ
This method is like _.flow except that it creates a function that
invokes the given functions from right to left.
Arguments
[funcs] (…(Function|Function[]): Functions to invoke.
Returns
(Function): Returns the new function.
Example
function square(n) {
return n * n;
}
var addSquare = _.flowRight(square, _.add);
addSquare(1, 2);
// → 9
_.identity(value)
# Ⓢ Ⓣ Ⓝ
This method returns the first argument given to it.
Arguments
value (*): Any value.
Returns
(*): Returns value.
Example
var object = { 'user': 'fred' };
_.identity(object) === object;
// → true
_.iteratee([func=_.identity])
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes func with the arguments of the created
function. If func is a property name the created callback returns the
property value for a given element. If func is an object the created
callback returns true for elements that contain the equivalent object
properties, otherwise it returns false.
Arguments
[func=_.identity] (*): The value to convert to a callback.
Returns
(Function): Returns the callback.
Example
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 }
];
// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(callback, func) {
var p = /^(\S+)\s*([<>])\s*(\S+)$/.exec(func);
return !p ? callback(func) : function(object) {
return (p[2] == '>' ? object[p[1]] > p[3] : object[p[1]] < p[3]);
};
});
_.filter(users, 'age > 36');
// → [{ 'user': 'fred', 'age': 40 }]
_.matches(source)
# Ⓢ Ⓣ Ⓝ
Creates a function that performs a partial deep comparison between a given
object and source, returning true if the given object has equivalent
property values, else false. The created function is equivalent to
_.isMatch with a source partially applied.
Note: This method supports comparing the same values as _.isEqual.
Arguments
source (Object): The object of property values to match.
Returns
(Function): Returns the new function.
Example
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false }
];
_.filter(users, _.matches({ 'age': 40, 'active': false }));
// → [{ 'user': 'fred', 'age': 40, 'active': false }]
_.matchesProperty(path, srcValue)
# Ⓢ Ⓣ Ⓝ
Creates a function that performs a partial deep comparison between the
value at path of a given object to srcValue, returning true if the
object value is equivalent, else false.
Note: This method supports comparing the same values as _.isEqual.
Arguments
path (Array|string): The path of the property to get.srcValue (*): The value to match.
Returns
(Function): Returns the new function.
Example
var users = [
{ 'user': 'barney' },
{ 'user': 'fred' }
];
_.find(users, _.matchesProperty('user', 'fred'));
// → { 'user': 'fred' }
_.method(path, [args])
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes the method at path of a given object.
Any additional arguments are provided to the invoked method.
Arguments
path (Array|string): The path of the method to invoke.[args] (…*): The arguments to invoke the method with.
Returns
(Function): Returns the new function.
Example
var objects = [
{ 'a': { 'b': { 'c': _.constant(2) } } },
{ 'a': { 'b': { 'c': _.constant(1) } } }
];
_.map(objects, _.method('a.b.c'));
// → [2, 1]
_.invokeMap(_.sortBy(objects, _.method(['a', 'b', 'c'])), 'a.b.c');
// → [1, 2]
_.methodOf(object, [args])
# Ⓢ Ⓣ Ⓝ
The opposite of _.method; this method creates a function that invokes
the method at a given path of object. Any additional arguments are
provided to the invoked method.
Arguments
object (Object): The object to query.[args] (…*): The arguments to invoke the method with.
Returns
(Function): Returns the new function.
Example
var array = _.times(3, _.constant),
object = { 'a': array, 'b': array, 'c': array };
_.map(['a[2]', 'c[0]'], _.methodOf(object));
// → [2, 0]
_.map([['a', '2'], ['c', '0']], _.methodOf(object));
// → [2, 0]
_.mixin([object=lodash], source, [options])
# Ⓢ Ⓣ Ⓝ
Adds all own enumerable function properties of a source object to the
destination object. If object is a function then methods are added to
its prototype as well.
Note: Use _.runInContext to create a pristine lodash function to
avoid conflicts caused by modifying the original.
Arguments
[object=lodash] (Function|Object): The destination object.source (Object): The object of functions to add.[options] (Object): The options object.[options.chain=true] (boolean): Specify whether the functions added are chainable.
Returns
(Function|Object): Returns object.
Example
function vowels(string) {
return _.filter(string, function(v) {
return /[aeiou]/i.test(v);
});
}
_.mixin({ 'vowels': vowels });
_.vowels('fred');
// → ['e']
_('fred').vowels().value();
// → ['e']
_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// → ['e']
_.noConflict()
# Ⓢ Ⓣ Ⓝ
Reverts the _ variable to its previous value and returns a reference to
the lodash function.
Returns
(Function): Returns the lodash function.
Example
var lodash = _.noConflict();
_.noop()
# Ⓢ Ⓣ Ⓝ
A no-operation function that returns undefined regardless of the
arguments it receives.
Example
var object = { 'user': 'fred' };
_.noop(object) === undefined;
// → true
_.nthArg([n=0])
# Ⓢ Ⓣ Ⓝ
Creates a function that returns its nth argument.
Arguments
[n=0] (number): The index of the argument to return.
Returns
(Function): Returns the new function.
Example
var func = _.nthArg(1);
func('a', 'b', 'c');
// → 'b'
_.over(iteratees)
# Ⓢ Ⓣ Ⓝ
Creates a function that invokes iteratees with the arguments provided
to the created function and returns their results.
Arguments
iteratees (…(Function|Function[]): The iteratees to invoke.
Returns
(Function): Returns the new function.
Example
var func = _.over(Math.max, Math.min);
func(1, 2, 3, 4);
// → [4, 1]
_.overEvery(predicates)
# Ⓢ Ⓣ Ⓝ
Creates a function that checks if all of the predicates return
truthy when invoked with the arguments provided to the created function.
Arguments
predicates (…(Function|Function[]): The predicates to check.
Returns
(Function): Returns the new function.
Example
var func = _.overEvery(Boolean, isFinite);
func('1');
// → true
func(null);
// → false
func(NaN);
// → false
_.overSome(predicates)
# Ⓢ Ⓣ Ⓝ
Creates a function that checks if any of the predicates return
truthy when invoked with the arguments provided to the created function.
Arguments
predicates (…(Function|Function[]): The predicates to check.
Returns
(Function): Returns the new function.
Example
var func = _.overSome(Boolean, isFinite);
func('1');
// → true
func(null);
// → true
func(NaN);
// → false
_.property(path)
# Ⓢ Ⓣ Ⓝ
Creates a function that returns the value at path of a given object.
Arguments
path (Array|string): The path of the property to get.
Returns
(Function): Returns the new function.
Example
var objects = [
{ 'a': { 'b': { 'c': 2 } } },
{ 'a': { 'b': { 'c': 1 } } }
];
_.map(objects, _.property('a.b.c'));
// → [2, 1]
_.map(_.sortBy(objects, _.property(['a', 'b', 'c'])), 'a.b.c');
// → [1, 2]
_.propertyOf(object)
# Ⓢ Ⓣ Ⓝ
The opposite of _.property; this method creates a function that returns
the value at a given path of object.
Arguments
object (Object): The object to query.
Returns
(Function): Returns the new function.
Example
var array = [0, 1, 2],
object = { 'a': array, 'b': array, 'c': array };
_.map(['a[2]', 'c[0]'], _.propertyOf(object));
// → [2, 0]
_.map([['a', '2'], ['c', '0']], _.propertyOf(object));
// → [2, 0]
_.range([start=0], end, [step=1])
# Ⓢ Ⓣ Ⓝ
Creates an array of numbers (positive and/or negative) progressing from
start up to, but not including, end. A step of -1 is used if a negative
start is specified without an end or step. If end is not specified
it’s set to start with start then set to 0.
Note: JavaScript follows the IEEE-754 standard for resolving
floating-point values which can produce unexpected results.
Arguments
[start=0] (number): The start of the range.end (number): The end of the range.[step=1] (number): The value to increment or decrement by.
Returns
(Array): Returns the new array of numbers.
Example
_.range(4);
// → [0, 1, 2, 3]
_.range(-4);
// → [0, -1, -2, -3]
_.range(1, 5);
// → [1, 2, 3, 4]
_.range(0, 20, 5);
// → [0, 5, 10, 15]
_.range(0, -4, -1);
// → [0, -1, -2, -3]
_.range(1, 4, 0);
// → [1, 1, 1]
_.range(0);
// → []
_.rangeRight([start=0], end, [step=1])
# Ⓢ Ⓣ Ⓝ
This method is like _.range except that it populates values in
descending order.
Arguments
[start=0] (number): The start of the range.end (number): The end of the range.[step=1] (number): The value to increment or decrement by.
Returns
(Array): Returns the new array of numbers.
Example
_.rangeRight(4);
// → [3, 2, 1, 0]
_.rangeRight(-4);
// → [-3, -2, -1, 0]
_.rangeRight(1, 5);
// → [4, 3, 2, 1]
_.rangeRight(0, 20, 5);
// → [15, 10, 5, 0]
_.rangeRight(0, -4, -1);
// → [-3, -2, -1, 0]
_.rangeRight(1, 4, 0);
// → [1, 1, 1]
_.rangeRight(0);
// → []
_.runInContext([context=root])
# Ⓢ Ⓣ Ⓝ
Create a new pristine lodash function using the context object.
Arguments
[context=root] (Object): The context object.
Returns
(Function): Returns a new lodash function.
Example
_.mixin({ 'foo': _.constant('foo') });
var lodash = _.runInContext();
lodash.mixin({ 'bar': lodash.constant('bar') });
_.isFunction(_.foo);
// → true
_.isFunction(_.bar);
// → false
lodash.isFunction(lodash.foo);
// → false
lodash.isFunction(lodash.bar);
// → true
// Use `context` to mock `Date#getTime` use in `_.now`.
var mock = _.runInContext({
'Date': function() {
return { 'getTime': getTimeMock };
}
});
// Create a suped-up `defer` in Node.js.
var defer = _.runInContext({ 'setTimeout': setImmediate }).defer;
_.times(n, [iteratee=_.identity])
# Ⓢ Ⓣ Ⓝ
Invokes the iteratee n times, returning an array of the results of
each invocation. The iteratee is invoked with one argument; (index).
Arguments
n (number): The number of times to invoke iteratee.[iteratee=_.identity] (Function): The function invoked per iteration.
Returns
(Array): Returns the array of results.
Example
_.times(3, String);
// → ['0', '1', '2']
_.times(4, _.constant(true));
// → [true, true, true, true]
_.toPath(value)
# Ⓢ Ⓣ Ⓝ
Converts value to a property path array.
Arguments
value (*): The value to convert.
Returns
(Array): Returns the new property path array.
Example
_.toPath('a.b.c');
// → ['a', 'b', 'c']
_.toPath('a[0].b.c');
// → ['a', '0', 'b', 'c']
var path = ['a', 'b', 'c'],
newPath = _.toPath(path);
console.log(newPath);
// → ['a', 'b', 'c']
console.log(path === newPath);
// → false
_.uniqueId([prefix=''])
# Ⓢ Ⓣ Ⓝ
Generates a unique ID. If prefix is given the ID is appended to it.
Arguments
[prefix=''] (string): The value to prefix the ID with.
Returns
(string): Returns the unique ID.
Example
_.uniqueId('contact_');
// → 'contact_104'
_.uniqueId();
// → '105'