collection

Methods for dealing with collections (Array or Objects).

contains(list, value):Boolean

Checks if collection contains value.

contains({a: 1, b: 2, c: 'bar'}, 2); // true
contains([1, 2, 3], 'foo');  // false

See: array/contains, object/contains

every(list, callback, [thisObj]):Boolean

Tests whether all values in the collection pass the test implemented by the provided callback.

var obj = {
    a: 1,
    b: 2,
    c: 3,
    d: 'string'
};

every(obj, isNumber); // false

See: array/every, object/every

filter(list, callback, [thisObj]):Array

Filter collection properties.

See: array/filter, object/filter

find(list, callback, [thisObj]):*

Loops through all the values in the collection and returns the first one that passes a truth test (callback).

Important: loop order over objects properties isn't guaranteed to be the same on all environments.

find({a: 'foo', b: 12}, isString); // 'foo'
find(['foo', 12], isNumber); // 12

See: array/find, object/find

forEach(list, callback, [thisObj])

Loop through all values of the collection.

See: array/forEach, object/forOwn

map(list, callback, [thisObj]):Array

Returns a new collection where the properties values are the result of calling the callback for each property in the original collection.

See: array/map, object/map

max(list, [iterator]):*

Returns maximum value inside collection or use a custom iterator to define how items should be compared.

See: min(), array/max, object/max

max({a: 100, b: 2, c: 1, d: 3, e: 200}); // 200
max(['foo', 'lorem', 'amet'], function(val){
    return val.length;
}); // 'lorem'

min(list, [iterator]):*

Returns minimum value inside collection or use a custom iterator to define how items should be compared.

See: max(), array/min, object/min

min([10, 2, 7]); // 2
min({a: 'foo', b: 'lorem', c: 'amet'}, function(val){
    return val.length;
}); // 'foo'

pluck(list, propName):Array

Extract a list of property values.

var users = [
    {
        name : 'John',
        age : 21
    },
    {
        name : 'Jane',
        age : 27
    }
];

pluck(users, 'name'); // ["John", "Jane"]
pluck(users, 'age'); // [21, 27]

users = {
    first: {
        name : 'John',
        age : 21
    },
    second: {
        name : 'Mary',
        age : 25
    }
};

pluck(users, 'name'); // ['John', 'Mary']

See: array/pluck, object/pluck

reduce(list, callback, initial, [thisObj]):*

Apply a function against an accumulator and each value in the collection as to reduce it to a single value.

var obj = {a: 1, b: 2, c: 3, d: 4};

function sum(prev, cur, key, list) {
    return prev + cur;
}

reduce(obj, sum); // 10

See: array/reduce, object/reduce

reject(list, fn, [thisObj]):Array

Creates a new array with all the elements that do not pass the truth test. Opposite of filter().

Example

var numbers = [1, 2, 3, 4, 5];
reject(numbers, function(x) { return (x % 2) !== 0; }); // [2, 4]

var obj = {a: 1, b: 2, c: 3, d: 4, e: 5};
reject(obj, function(x) { return (x % 2) !== 0; }); // [2, 4]

See: array/reject, object/reject

size(list):Number

Returns the number of values in the collection.

var obj = {
    foo : 1,
    bar : 2,
    lorem : 3
};
size(obj);     // 3
size([1,2,3]); // 3
size(null);    // 0

See: object/size

some(list, callback, [thisObj]):Boolean

Tests whether any values in the collection pass the test implemented by the provided callback.

var obj = {
    a: 1,
    b: 2,
    c: 3,
    d: 'string'
};

some(obj, isNumber);      // true
some(obj, isString);      // true
some([1, 2, 3], isNumber) // true
some([1, 2, 3], isString) // false

See: array/some, object/some

For more usage examples check specs inside /tests folder. Unit tests are the best documentation you can get...

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