_.compact(array)

Creates an array with all falsey values of array removed. The values false, null, 0, "", undefined and NaN are all falsey.

Arguments

1. array (Array): The array to compact.

Returns

(Array): Returns a new filtered array.

Example

_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

_.difference(array [, array1, array2, …])

Creates an array of array elements not present in the other arrays using strict equality for comparisons, i.e. ===.

Arguments

1. array (Array): The array to process.
2. [array1, array2, ...] (Array): Arrays to check.

Returns

(Array): Returns a new array of array elements not present in the other arrays.

Example

_.difference([1, 2, 3, 4, 5], [5, 2, 10]);
// => [1, 3, 4]

_.findIndex(array [, callback=identity, thisArg])

This method is similar to _.find, except that it returns the index of the element that passes the callback check, instead of the element itself.

Arguments

1. array (Array): The array to search.
2. [callback=identity] (Function|Object|String): The function called per iteration. If a property name or object is passed, it will be used to create a “.pluck” or “.where” style callback, respectively.
3. [thisArg] (Mixed): The this binding of callback.

Returns

(Mixed): Returns the index of the found element, else -1.

Example

_.findIndex(['apple', 'banana', 'beet'], function(food) {
  return /^b/.test(food);
});
// => 1

_.first(array [, callback|n, thisArg])

Gets the first element of the array. If a number n is passed, the first n elements of the array are returned. If a callback function is passed, elements at the beginning of the array are returned as long as the callback returns truthy. The callback is bound to thisArg and invoked with three arguments; (value, index, array).

If a property name is passed for callback, the created “_.pluck” style callback will return the property value of the given element.

If an object is passed for callback, the created “_.where” style callback will return true for elements that have the properties of the given object, else false.

Aliases

head, take

Arguments

1. array (Array): The array to query.
2. [callback|n] (Function|Object|Number|String): The function called per element or the number of elements to return. If a property name or object is passed, it will be used to create a “.pluck” or “.where” style callback, respectively.
3. [thisArg] (Mixed): The this binding of callback.

Returns

(Mixed): Returns the first element(s) of array.

Example

_.first([1, 2, 3]);
// => 1
_.first([1, 2, 3], 2);
// => [1, 2]
_.first([1, 2, 3], function(num) {
  return num < 3;
});
// => [1, 2]
var food = [
  { 'name': 'banana', 'organic': true },
  { 'name': 'beet',   'organic': false },
];
// using "_.pluck" callback shorthand
_.first(food, 'organic');
// => [{ 'name': 'banana', 'organic': true }]
var food = [
  { 'name': 'apple',  'type': 'fruit' },
  { 'name': 'banana', 'type': 'fruit' },
  { 'name': 'beet',   'type': 'vegetable' }
];
// using "_.where" callback shorthand
_.first(food, { 'type': 'fruit' });
// => [{ 'name': 'apple', 'type': 'fruit' }, { 'name': 'banana', 'type': 'fruit' }]

_.flatten(array [, isShallow=false, callback=identity, thisArg])

Flattens a nested array (the nesting can be to any depth). If isShallow is truthy, array will only be flattened a single level. If callback is passed, each element of array is passed through a callback before flattening. The callback is bound to thisArg and invoked with three arguments; (value, index, array).

If a property name is passed for callback, the created “_.pluck” style callback will return the property value of the given element.

If an object is passed for callback, the created “_.where” style callback will return true for elements that have the properties of the given object, else false.

Arguments

1. array (Array): The array to flatten.
2. [isShallow=false] (Boolean): A flag to indicate only flattening a single level.
3. [callback=identity] (Function|Object|String): The function called per iteration. If a property name or object is passed, it will be used to create a “.pluck” or “.where” style callback, respectively.
4. [thisArg] (Mixed): The this binding of callback.

Returns

(Array): Returns a new flattened array.

Example

_.flatten([1, [2], [3, [[4]]]]);
// => [1, 2, 3, 4];
_.flatten([1, [2], [3, [[4]]]], true);
// => [1, 2, 3, [[4]]];
var stooges = [
  { 'name': 'curly', 'quotes': ['Oh, a wise guy, eh?', 'Poifect!'] },
  { 'name': 'moe', 'quotes': ['Spread out!', 'You knucklehead!'] }
];
// using "_.pluck" callback shorthand
_.flatten(stooges, 'quotes');
// => ['Oh, a wise guy, eh?', 'Poifect!', 'Spread out!', 'You knucklehead!']

_.indexOf(array, value [, fromIndex=0])

Gets the index at which the first occurrence of value is found using strict equality for comparisons, i.e. ===. If the array is already sorted, passing true for fromIndex will run a faster binary search.

Arguments

1. array (Array): The array to search.
2. value (Mixed): The value to search for.
3. [fromIndex=0] (Boolean|Number): The index to search from or true to perform a binary search on a sorted array.

Returns

(Number): Returns the index of the matched value or -1.

Example

_.indexOf([1, 2, 3, 1, 2, 3], 2);
// => 1
_.indexOf([1, 2, 3, 1, 2, 3], 2, 3);
// => 4
_.indexOf([1, 1, 2, 2, 3, 3], 2, true);
// => 2

_.initial(array [, callback|n=1, thisArg])

Gets all but the last element of array. If a number n is passed, the last n elements are excluded from the result. If a callback function is passed, elements at the end of the array are excluded from the result as long as the callback returns truthy. The callback is bound to thisArg and invoked with three arguments; (value, index, array).

If a property name is passed for callback, the created “_.pluck” style callback will return the property value of the given element.

If an object is passed for callback, the created “_.where” style callback will return true for elements that have the properties of the given object, else false.

Arguments

1. array (Array): The array to query.
2. [callback|n=1] (Function|Object|Number|String): The function called per element or the number of elements to exclude. If a property name or object is passed, it will be used to create a “.pluck” or “.where” style callback, respectively.
3. [thisArg] (Mixed): The this binding of callback.

Returns

(Array): Returns a slice of array.

Example

_.initial([1, 2, 3]);
// => [1, 2]
_.initial([1, 2, 3], 2);
// => [1]
_.initial([1, 2, 3], function(num) {
  return num > 1;
});
// => [1]
var food = [
  { 'name': 'beet',   'organic': false },
  { 'name': 'carrot', 'organic': true }
];
// using "_.pluck" callback shorthand
_.initial(food, 'organic');
// => [{ 'name': 'beet',   'organic': false }]
var food = [
  { 'name': 'banana', 'type': 'fruit' },
  { 'name': 'beet',   'type': 'vegetable' },
  { 'name': 'carrot', 'type': 'vegetable' }
];
// using "_.where" callback shorthand
_.initial(food, { 'type': 'vegetable' });
// => [{ 'name': 'banana', 'type': 'fruit' }]

_.intersection([array1, array2, …])

Computes the intersection of all the passed-in arrays using strict equality for comparisons, i.e. ===.

Arguments

1. [array1, array2, ...] (Array): Arrays to process.

Returns

(Array): Returns a new array of unique elements that are present in all of the arrays.

Example

_.intersection([1, 2, 3], [101, 2, 1, 10], [2, 1]);
// => [1, 2]

_.last(array [, callback|n, thisArg])

Gets the last element of the array. If a number n is passed, the last n elements of the array are returned. If a callback function is passed, elements at the end of the array are returned as long as the callback returns truthy. The callback is bound to thisArg and invoked with three arguments;(value, index, array).

If a property name is passed for callback, the created “_.pluck” style callback will return the property value of the given element.

If an object is passed for callback, the created “_.where” style callback will return true for elements that have the properties of the given object, else false.

Arguments

1. array (Array): The array to query.
2. [callback|n] (Function|Object|Number|String): The function called per element or the number of elements to return. If a property name or object is passed, it will be used to create a “.pluck” or “.where” style callback, respectively.
3. [thisArg] (Mixed): The this binding of callback.

Returns

(Mixed): Returns the last element(s) of array.

Example

_.last([1, 2, 3]);
// => 3
_.last([1, 2, 3], 2);
// => [2, 3]
_.last([1, 2, 3], function(num) {
  return num > 1;
});
// => [2, 3]
var food = [
  { 'name': 'beet',   'organic': false },
  { 'name': 'carrot', 'organic': true }
];
// using "_.pluck" callback shorthand
_.last(food, 'organic');
// => [{ 'name': 'carrot', 'organic': true }]
var food = [
  { 'name': 'banana', 'type': 'fruit' },
  { 'name': 'beet',   'type': 'vegetable' },
  { 'name': 'carrot', 'type': 'vegetable' }
];
// using "_.where" callback shorthand
_.last(food, { 'type': 'vegetable' });
// => [{ 'name': 'beet', 'type': 'vegetable' }, { 'name': 'carrot', 'type': 'vegetable' }]

_.lastIndexOf(array, value [, fromIndex=array.length-1])

Gets the index at which the last occurrence of value is found using strict equality for comparisons, i.e. ===. If fromIndex is negative, it is used as the offset from the end of the collection.

Arguments

1. array (Array): The array to search.
2. value (Mixed): The value to search for.
3. [fromIndex=array.length-1] (Number): The index to search from.

Returns

(Number): Returns the index of the matched value or -1.

Example

_.lastIndexOf([1, 2, 3, 1, 2, 3], 2);
// => 4
_.lastIndexOf([1, 2, 3, 1, 2, 3], 2, 3);
// => 1

_.range([start=0], end [, step=1])

Creates an array of numbers (positive and/or negative) progressing from start up to but not including end.

Arguments

1. [start=0] (Number): The start of the range.
2. end (Number): The end of the range.
3. [step=1] (Number): The value to increment or decrement by.

Returns

(Array): Returns a new range array.

Example

_.range(10);
// => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
_.range(1, 11);
// => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
_.range(0, 30, 5);
// => [0, 5, 10, 15, 20, 25]
_.range(0, -10, -1);
// => [0, -1, -2, -3, -4, -5, -6, -7, -8, -9]
_.range(0);
// => []

_.rest(array [, callback|n=1, thisArg])

The opposite of _.initial, this method gets all but the first value of array. If a number n is passed, the first n values are excluded from the result. If a callback function is passed, elements at the beginning of the array are excluded from the result as long as the callback returns truthy. The callback is bound to thisArg and invoked with three arguments; (value, index, array).

If a property name is passed for callback, the created “_.pluck” style callback will return the property value of the given element.

If an object is passed for callback, the created “_.where” style callback will return true for elements that have the properties of the given object, else false.

Aliases

drop, tail

Arguments

1. array (Array): The array to query.
2. [callback|n=1] (Function|Object|Number|String): The function called per element or the number of elements to exclude. If a property name or object is passed, it will be used to create a “.pluck” or “.where” style callback, respectively.
3. [thisArg] (Mixed): The this binding of callback.

Returns

(Array): Returns a slice of array.

Example

_.rest([1, 2, 3]);
// => [2, 3]
_.rest([1, 2, 3], 2);
// => [3]
_.rest([1, 2, 3], function(num) {
  return num < 3;
});
// => [3]
var food = [
  { 'name': 'banana', 'organic': true },
  { 'name': 'beet',   'organic': false },
];
// using "_.pluck" callback shorthand
_.rest(food, 'organic');
// => [{ 'name': 'beet', 'organic': false }]
var food = [
  { 'name': 'apple',  'type': 'fruit' },
  { 'name': 'banana', 'type': 'fruit' },
  { 'name': 'beet',   'type': 'vegetable' }
];
// using "_.where" callback shorthand
_.rest(food, { 'type': 'fruit' });
// => [{ 'name': 'beet', 'type': 'vegetable' }]

_.sortedIndex(array, value [, callback=identity, thisArg])

Uses a binary search to determine the smallest index at which the value should be inserted into array in order to maintain the sort order of the sorted array. If callback is passed, it will be executed for value and each element in array to compute their sort ranking. The callback is bound to thisArg and invoked with one argument; (value).

If a property name is passed for callback, the created “_.pluck” style callback will return the property value of the given element.

If an object is passed for callback, the created “_.where” style callback will return true for elements that have the properties of the given object, else false.

Arguments

1. array (Array): The array to inspect.
2. value (Mixed): The value to evaluate.
3. [callback=identity] (Function|Object|String): The function called per iteration. If a property name or object is passed, it will be used to create a “.pluck” or “.where” style callback, respectively.
4. [thisArg] (Mixed): The this binding of callback.

Returns

(Number): Returns the index at which the value should be inserted into array.

Example

_.sortedIndex([20, 30, 50], 40);
// => 2
// using "_.pluck" callback shorthand
_.sortedIndex([{ 'x': 20 }, { 'x': 30 }, { 'x': 50 }], { 'x': 40 }, 'x');
// => 2
var dict = {
  'wordToNumber': { 'twenty': 20, 'thirty': 30, 'fourty': 40, 'fifty': 50 }
};
_.sortedIndex(['twenty', 'thirty', 'fifty'], 'fourty', function(word) {
  return dict.wordToNumber[word];
});
// => 2
_.sortedIndex(['twenty', 'thirty', 'fifty'], 'fourty', function(word) {
  return this.wordToNumber[word];
}, dict);
// => 2

_.union([array1, array2, …])

Computes the union of the passed-in arrays using strict equality for comparisons, i.e. ===.

Arguments

1. [array1, array2, ...] (Array): Arrays to process.

Returns

(Array): Returns a new array of unique values, in order, that are present in one or more of the arrays.

Example

_.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
// => [1, 2, 3, 101, 10]

_.uniq(array [, isSorted=false, callback=identity, thisArg])

Creates a duplicate-value-free version of the array using strict equality for comparisons, i.e. ===. If the array is already sorted, passing true for isSorted will run a faster algorithm. If callback is passed, each element of array is passed through the callback before uniqueness is computed. The callback is bound to thisArg and invoked with three arguments; (value, index, array).

If a property name is passed for callback, the created “_.pluck” style callback will return the property value of the given element.

If an object is passed for callback, the created “_.where” style callback will return true for elements that have the properties of the given object, else false.

Aliases

unique

Arguments

1. array (Array): The array to process.
2. [isSorted=false] (Boolean): A flag to indicate that the array is already sorted.
3. [callback=identity] (Function|Object|String): The function called per iteration. If a property name or object is passed, it will be used to create a “.pluck” or “.where” style callback, respectively.
4. [thisArg] (Mixed): The this binding of callback.

Returns

(Array): Returns a duplicate-value-free array.

Example

_.uniq([1, 2, 1, 3, 1]);
// => [1, 2, 3]
_.uniq([1, 1, 2, 2, 3], true);
// => [1, 2, 3]
_.uniq(['A', 'b', 'C', 'a', 'B', 'c'], function(letter) { return letter.toLowerCase(); });
// => ['A', 'b', 'C']
_.uniq([1, 2.5, 3, 1.5, 2, 3.5], function(num) { return this.floor(num); }, Math);
// => [1, 2.5, 3]
// using "_.pluck" callback shorthand
_.uniq([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

_.unzip(array)

The inverse of _.zip, this method splits groups of elements into arrays composed of elements from each group at their corresponding indexes.

Arguments

1. array (Array): The array to process.

Returns

(Array): Returns a new array of the composed arrays.

Example

_.unzip([['moe', 30, true], ['larry', 40, false]]);
// => [['moe', 'larry'], [30, 40], [true, false]];

_.without(array [, value1, value2, …])

Creates an array with all occurrences of the passed values removed using strict equality for comparisons, i.e. ===.

Arguments

1. array (Array): The array to filter.
2. [value1, value2, ...] (Mixed): Values to remove.

Returns

(Array): Returns a new filtered array.

Example

_.without([1, 2, 1, 0, 3, 1, 4], 0, 1);
// => [2, 3, 4]

_.zip([array1, array2, …])

Groups the elements of each array at their corresponding indexes. Useful for separate data sources that are coordinated through matching array indexes. For a matrix of nested arrays, _.zip.apply(...) can transpose the matrix in a similar fashion.

Arguments

1. [array1, array2, ...] (Array): Arrays to process.

Returns

(Array): Returns a new array of grouped elements.

Example

_.zip(['moe', 'larry'], [30, 40], [true, false]);
// => [['moe', 30, true], ['larry', 40, false]]

_.zipObject(keys [, values=[]])

Creates an object composed from arrays of keys and values. Pass either a single two dimensional array, i.e. [[key1, value1], [key2, value2]], or two arrays, one of keys and one of corresponding values.

Aliases

object

Arguments

1. keys (Array): The array of keys.
2. [values=[]] (Array): The array of values.

Returns

(Object): Returns an object composed of the given keys and corresponding values.

Example

_.zipObject(['moe', 'larry'], [30, 40]);
// => { 'moe': 30, 'larry': 40 }