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Collections

Understand the Collections API of the Athenna Framework.

Introduction​

The Collection class from @athenna/common provides a fluent, convenient wrapper for working with arrays of data. For example, check out the following code. We'll create a new instance of Collection using an array of users, remove all empty elements get all elements where the id is 1, 2 or 3, order everything in ascending mode by name and then get only the value of the property name of each one of the elements:

const users = [
    { id: 1, name: 'Marcelo Oliveira'},
    { id: 2, name: 'Vinicius Campelo' },
    { id: 3, name: 'Marcelo Amaral' },
    { id: 4, name: 'Ilson Bolzan' },
    { id: 5, name: 'Thales Salgado' },
    { id: 6, name: 'Vinicius Pulgatti' },
    { id: 7, name: 'Rodrigo Kamada' },
    { id: 8, name: 'Danyla Andrade' },
    { id: 9, name: 'Gustavo Raeski' },
    { id: 10, name: 'Marcelo Zilio' },
    { id: 11, name: 'Wladimir Mangelardo' },
    undefined,
    null
]

const namesCollection = new Collection(users)
    .reject(user => !user) // We could use just "filter()" here too.
    .whereIn('id', [1, 2, 3])
    .orderBy('name')
    .pluck('name')

As you can see, the Collection class allows you to chain its methods to perform fluent mapping and reducing of the underlying array. In general, collections are immutable, meaning every Collection method returns an entirely new Collection instance.

Creating collections​

As you can see in the example above, creating a collection is as simples as:

const collection = new Collection([1, 2, 3])

Simplifying even more: Athenna has extended the Array class to simply convert an array to a collection using the toAthennaCollection() method:

const numbers = [1, 2, 3]

const collection = numbers.toAthennaCollection()
info

The results of the collection method of Database and Model class are always returned as a Collection.

Extending collections​

Collections are extendable, which allows you to add additional methods to the Collection class at run time. The Collection class' macro method accepts a closure that will be executed when your macro is called. The macro closure may access the collection's other methods via this, just as if it were a real method of the collection class. For example, the following code adds a toUpper method to the Collection class:

import { Collection } from '@athenna/common'

Collection.macro('toUpper', function () {
  return this.map(item => item.toUpperCase())
})

const collection = new Collection(['joão', 'thais'])
const upper = collection.toUpper() // ['JOÃO', 'THAIS']
tip

Typically, you should declare collection macros in the boot method of a service provider.

Macro arguments​

If necessary, you may define macros that accept additional arguments:

Collection.macro('remove', function (key) {
  return this.map(item => {
      if (item[key]) {
          delete item[key]
      }

      return item
  })
})

const collection = new Collection([{ id: 1, name: 'João' }, { id: 2, name: 'Victor' }])

collection.remove('name').all() // [{ id: 1 }, { id: 2 }]

Available methods​

For the majority of the remaining collection documentation, we'll discuss each method available on the Collection class. Remember, all of these methods may be chained to fluently manipulate the underlying array. Furthermore, almost every method returns a new Collection instance, allowing you to preserve the original copy of the collection when necessary:

all()​

The all method returns the underlying array or object represented by the collection:

new Collection([1, 2, 3]).all()

// [1, 2, 3]
new Collection({
  firstname: 'Darwin',
  lastname: 'Núñez',
}).all()

// {
//   firstname: 'Darwin',
//   lastname: 'Núñez',
// }

average()​

Alias for the avg() method

avg()​

The avg method returns the average of all items in the collection:

new Collection([1, 3, 3, 7]).avg()

// 3.5

If the collection contains nested arrays or objects, you should pass a key to use for determining which values to calculate the average:

const collection = new Collection([
  {
    name: 'My story',
    pages: 176,
  },
  {
    name: 'Fantastic Beasts and Where to Find Them',
    pages: 1096,
  },
])

collection.avg('pages')

// 636

You may also define a callback function

const collection = new Collection([
  {
    name: 'My story',
    pages: 176,
  },
  {
    name: 'Fantastic Beasts and Where to Find Them',
    pages: 1096,
  },
])

collection.avg(book => book.pages)

// 636

chunk()​

The chunk method breaks the collection into multiple, smaller collections of a given size:

const collection = new Collection([1, 2, 3, 4, 5, 6, 7])

const chunks = collection.chunk(4)

chunks.all()

// [[1, 2, 3, 4], [5, 6, 7]]

collapse()​

The collapse method collapses a collection of arrays into a single, flat collection:

const collection = new Collection([[1], [{}, 5, {}], ['xoxo']])

const collapsed = collection.collapse()

collapsed.all()

// [1, {}, 5, {}, 'xoxo']
const collection = new Collection([[1, 2, 3], [4, 5, 6], [7, 8, 9]])

const collapsed = collection.collapse()

collapsed.all()

// [1, 2, 3, 4, 5, 6, 7, 8, 9]

combine()​

The combine method combines the keys of the collection with the values of another array or collection:

const collection = new Collection(['name', 'number'])

const combine = collection.combine(['Mohamed Salah', 11])

combine.all()

// {
//   name: 'Mohamed Salah',
//   number: 11
// }

concat()​

The concat method is used to merge two or more collections/arrays/objects:

You can also concat() an array of objects, or a multidimensional array

const collection = new Collection([1, 2, 3])

let concatenated = collection.concat(['a', 'b', 'c'])

concatenated = concatenated.concat({
  name: 'Mohamed Salah',
  number: 11,
})

concatenated.all()

// [1, 2, 3, 'a', 'b', 'c', 'Mohamed Salah', 11]

contains()​

The contains method determines whether the collection contains a given item:

const collection = new Collection({
  name: 'Mohamed Salah',
  number: 11,
})

collection.contains('name')
// true

collection.contains('age')
// false

collection.contains('Mohamed Salah')
// true

You may also work with arrays

const collection = new Collection([1, 2, 3])

collection.contains(3)
// true

You may also pass a key / value pair to the contains method, which will determine if the given pair exists in the collection:

const collection = new Collection({
  name: 'Mohamed Salah',
  number: 11,
})

collection.contains('name', 'Steve Jobs')
// false

Finally, you may also pass a callback to the contains method to perform your own truth test:

const collection = new Collection([1, 2, 3, 4, 5])

collection.contains((value, key) => value > 5)

// false

containsOneItem()​

The containsOneItem method returns true if the collection contains exactly one item otherwise, false is returned:

new Collection([1]).containsOneItem()
// true

new Collection({ firstname: 'Luis' }).containsOneItem()
// true

new Collection('value').containsOneItem()
// true

new Collection([1, 2, 3]).containsOneItem()
//  false

new Collection({ firstname: 'Luis', lastname: 'Díaz' }).containsOneItem()
// false

new Collection().containsOneItem()
// false

new Collection([]).containsOneItem()
// false

new Collection({}).containsOneItem()
// false

count()​

The count method returns the total number of items in the collection:

const collection = new Collection([1, 2, 3, 4])

collection.count()

// 4

countBy()​

The countBy method counts the occurences of values in the collection. By default, the method counts the occurrences of every element:

const collection = new Collection([1, 2, 2, 2, 3])

const counted = collection.countBy()

counted.all()

// {
//   1: 1,
//   2: 3,
//   3: 1,
// }

However, you pass a callback to the countBy method to count all items by a custom value:

const collection = new Collection([
  'mohamed.salah@gmail.com',
  'darwin.nunez@yahoo.com',
  'roberto.firmino@gmail.com',
])

const counted = collection.countBy(email => email.split('@')[1])

counted.all()

// {
//   'gmail.com': 2,
//   'yahoo.com': 1,
// }

crossJoin()​

The crossJoin method cross joins the collection with the given array or collection, returning all possible permutations:

const collection = new Collection([1, 2])

const joined = collection.crossJoin(['a', 'b'])

joined.all()

// [
//   [1, 'a'],
//   [1, 'b'],
//   [2, 'a'],
//   [2, 'b'],
// ]

dd()​

The dd method will console.log the collection and exit the current process:

const collection = new Collection([1, 2, 3]).dd()

// Collection { items: [ 1, 2, 3 ] }
// (Exits node.js process)

diff()​

The diff method compares the collection against another collection or a plain array based on its values. This method will return the values in the original collection that are not present in the given collection:

const collection = new Collection([1, 2, 3, 4, 5])

const diff = collection.diff([1, 2, 3, 9])

diff.all()

// [4, 5]

diffAssoc()​

The diffAssoc method compares the collection against another collection or a plain object based on its keys and values. This method will return the key / value pairs in the original collection that are not present in the given collection:

const collection = new Collection({
  color: 'orange',
  type: 'fruit',
  remain: 6,
})

const diff = collection.diffAssoc({
  color: 'yellow',
  type: 'fruit',
  remain: 3,
  used: 6,
})

diff.all()

// { color: 'orange', remain: 6 }

diffKeys()​

The diffKeys method compares the collection against another collection or a plain object based on its keys. This method will return the key / value pairs in the original collection that are not present in the given collection:

const collection = new Collection({
  a: 'a',
  b: 'b',
  c: 'c',
  d: 'd',
})

const diff = collection.diffKeys({
  b: 'b',
  d: 'd',
})

diff.all()

// { a: 'a', c: 'c' }

doesntContain()​

The doesntContain method determines whether the collection does not contain a given item. You may pass a closure to the doesntContain method to determine if an element does not exist in the collection matching a given truth test:

const collection = new Collection([1, 2, 3, 4, 5])

collection.doesntContain(value => value < 5)

// false
const collection = new Collection([1, 2, 3])

collection.doesntContain(4)
// true

You may also use doesntContain on object based collections:

const collection = new Collection({
  name: 'Mohamed Salah',
  number: 11,
})

collection.doesntContain('Mohamed Salah')
// false

collection.doesntContain('Darwin Núñez')
// true

You may also pass a key / value pair to the contains method, which will determine if the given pair exists in the collection:

const collection = new Collection({
  name: 'Mohamed Salah',
  number: 11,
})

collection.doesntContain('name', 'Darwin Núñez')
// true

dump()​

The dump method outputs the results at that moment and then continues processing:

new Collection([1, 2, 3, 4])
  .dump()
  .map(item => item * 2)
  .dump()

// Collection { items: [ 1, 2, 3, 4 ] }
// Collection { items: [ 2, 4, 6, 8 ] }

duplicates()​

The duplicates method retrieves and returns duplicate values from the collection:

const collection = new Collection(['a', 'b', 'a', 'c', 'b'])

const duplicates = collection.duplicates()

duplicates.all()

// { 2: 'a', 4: 'b' }

each()​

The each method iterates over the items in the collection and passes each item to a callback:

let sum = 0

const collection = new Collection([1, 3, 3, 7])

collection.each((item) => {
  sum += item
})

// console.log(sum)
// 14

If you would like to stop iterating through the items, you may return false from your callback:

let sum = 0

const collection = new Collection([1, 3, 3, 7])

collection.each((item) => {
  sum += item

  if (sum > 5) {
    return false
  }
})

// console.log(sum)
// 7

eachSpread()​

The eachSpread method iterates over the collection's items, passing each nested item value into the given callback:

const collection = new Collection([['John Doe', 35], ['Jane Doe', 33]])

collection.eachSpread((name, age) => {
  //
})

You may stop iterating through the items by returning false from the callback:

collection.eachSpread((name, age) => false)

every()​

The every method may be used to verify that all elements of a collection pass a given truth test:

new Collection([1, 2, 3, 4]).every((value, key) => value > 2)

// false

except()​

The except method returns all items in the collection except for those with the specified keys:

const collection = new Collection({
  product_id: 1,
  price: 100,
  discount: false,
})

const filtered = collection.except(['price', 'discount'])

filtered.all()

// { product_id: 1 }
new Collection([1, 2, 3, 4])
  .except([2, 12])
  .all()

// [1, 3, 4]

For the inverse of except, see the only method.

filter()​

The filter method filters the collection using the given callback, keeping only those items that pass a given truth test:

const collection = new Collection([1, 2, 3, 4])

const filtered = collection.filter((value, key) => value > 2)

filtered.all()

// [3, 4]

If no callback is supplied, all entries of the collection that are equivalent to false will be removed:

const collection = new Collection([
  0,
  1,
  2,
  null,
  3,
  4,
  undefined,
  5,
  6,
  7,
  [],
  8,
  9,
  {},
  10,
])

const filtered = collection.filter()

filtered.all()

// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

For the inverse of filter, see the reject method.

first()​

The first method returns the first element in the collection that passes a given truth test:

new Collection([1, 2, 3, 4]).first(item => item > 1)

// 2

You may also call the first method with no arguments to get the first element in the collection. If the collection is empty, null is returned:

new Collection([1, 2, 3, 4]).first()

// 1

firstOrFail()​

The firstOrFail method returns the first element in the collection, or throws an error if there are no elements:

new Collection([1, 2, 3, 4]).firstOrFail(item => item > 1)

// 2
new Collection([1, 2, 3, 4]).firstOrFail(item => item > 4)

// Error ('Item not found.') is thrown.

You may also call the firstOrFail method with no arguments to get the first element in the collection. If the collection is empty, an error is thrown:

new Collection([1, 2, 3, 4]).firstOrFail()

// 1
new Collection().firstOrFail()

// Error ('Item not found.') is thrown.

Like the where method, you may also pass an attribute, operator, and value:

const collection = new Collection([
  { product: 'Desk', price: 200, discounted: true },
  { product: 'Chair', price: 100, discounted: true },
  { product: 'Bookcase', price: 150, discounted: true },
  { product: 'Door', price: 100 },
])

collection.firstOrFail('product', '=', 'Desk')

// { product: 'Desk', price: 200, discounted: true }

firstWhere()​

The firstWhere method returns the first element in the collection with the given key / value pair:

const collection = new Collection([
  { name: 'Regena', age: 12 },
  { name: 'Linda', age: 14 },
  { name: 'Diego', age: 23 },
  { name: 'Linda', age: 84 },
])

collection.firstWhere('name', 'Linda')

// { name: 'Linda', age: 14 }

flatMap()​

The flatMap method iterates through the collection and passes each value to the given callback. The callback is free to modify the item and return it, thus forming a new collection of modified items. Then, the array is flattened by a level:

const collection = new Collection([
  {
    name: 'Darwin Núñez',
    number: 27,
  },
  {
    name: 'Mohamed Salah',
    number: 11,
  },
])

const flatMapped = collection.flatMap(value => value.name.toUpperCase())

flatMapped.all()

// ['DARWIN NÚÑEZ', 'MOHAMED SALAH']

flatten()​

The flatten method flattens a multi-dimensional collection into a single dimension:

const collection = new Collection({
  club: 'Liverpool',
  players: ['Salah', 'Firmino', 'Núñez'],
})

const flattened = collection.flatten()

flattened.all()

// ['Liverpool', 'Salah', 'Firmino', 'Núñez']

You may optionally pass the function a "depth" argument:

const collection = new Collection({
  Apple: [
    {
      name: 'iPhone 6S',
      brand: 'Apple',
    },
  ],
  Samsung: [
    {
      name: 'Galaxy S7',
      brand: 'Samsung',
    },
  ],
})

const flattened = collection.flatten(1)

flattened.all()

// [
//   { name: 'iPhone 6S', brand: 'Apple' },
//   { name: 'Galaxy S7', brand: 'Samsung' },
// ]

In this example, calling flatten without providing the depth would have also flattened the nested arrays, resulting in ['iPhone 6S', 'Apple', 'Galaxy S7', 'Samsung']. Providing a depth allows you to restrict the levels of nested arrays that will be flattened.

flip()​

The flip method swaps the collection's keys with their corresponding values:

const collection = new Collection({
  name: 'Darwin Núñez',
  number: 27,
})

const flipped = collection.flip()

flipped.all()

// {
//   'Darwin Núñez': 'name',
//   '27': 'number',
// }

forPage()​

The forPage method returns a new collection containing the items that would be present on a given page number. The method accepts the page number as its first argument and the number of items to show per page as its second argument:

const collection = new Collection([1, 2, 3, 4, 5, 6, 7, 8, 9])

const forPage = collection.forPage(2, 3)

forPage.all()

// [4, 5, 6]

forget()​

The forget method removes an item from the collection by its key:

const collection = new Collection({
  name: 'Darwin Núñez',
  number: 27,
})

collection.forget('number')

collection.all()

// {
//   name: 'Darwin Núñez',
// }

Unlike most other collection methods, forget does not return a new modified collection it modifies the collection it is called on.

get()​

The get method returns the item at a given key or index. If the key or index does not exist, null is returned:

const collection = new Collection({
  firstname: 'Mohamed',
  lastname: 'Salah',
})

collection.get('lastname')

// Salah

collection.get('middlename')

// null
const collection = new Collection(['a', 'b', 'c'])

collection.get(1)

// b

You may optionally pass a default value as the second argument:

const collection = new Collection({
  firstname: 'Mohamed',
  lastname: 'Salah',
})

collection.get('middlename', 'default-value')
// default-value

You may even pass a callback as the default value. The result of the callback will be returned if the specified key does not exist:

const collection = new Collection({
  firstname: 'Mohamed',
  lastname: 'Salah',
})

collection.get('middlename', () => 'default-value')

// default-value

groupBy()​

The groupBy method groups the collection's items into multiple collections by a given key:

If you want to group the collection by keys as a plain object, see mapToGroups

const collection = new Collection([
  {
    product: 'Chair',
    manufacturer: 'IKEA',
  },
  {
    product: 'Desk',
    manufacturer: 'IKEA',
  },
  {
    product: 'Chair',
    manufacturer: 'Herman Miller',
  },
])

const grouped = collection.groupBy('manufacturer')

grouped.all()

// {
//   IKEA: Collection {
//     items: [
//        {
//          id: 100,
//          product: 'Chair',
//          manufacturer: 'IKEA',
//          price: '1490 NOK',
//        },
//        {
//          id: 150,
//          product: 'Desk',
//          manufacturer: 'IKEA',
//          price: '900 NOK',
//        },
//      ],
//   },
//   'Herman Miller': Collection {
//     items: [
//       {
//         id: 200,
//         product: 'Chair',
//         manufacturer: 'Herman Miller',
//         price: '9990 NOK',
//       },
//     ],
//   },
// }

In addition to passing a string key, you may also pass a callback. The callback should return the value you wish to key the group by:

const collection = new Collection([
  {
    product: 'Chair',
    manufacturer: 'IKEA',
  },
  {
    product: 'Desk',
    manufacturer: 'IKEA',
  },
  {
    product: 'Chair',
    manufacturer: 'Herman Miller',
  },
])

const grouped = collection.groupBy((item, key) => item.manufacturer.substring(0, 3))

grouped.all()

// {
//   IKE: Collection {
//     items: [
//       {
//         id: 100,
//         product: 'Chair',
//         manufacturer: 'IKEA',
//         price: '1490 NOK',
//       },
//       {
//         id: 150,
//         product: 'Desk',
//         manufacturer: 'IKEA',
//         price: '900 NOK',
//       },
//     ],
//   },
//   Her: Collection {
//     items: [
//       {
//         id: 200,
//         product: 'Chair',
//         manufacturer: 'Herman Miller',
//         price: '9990 NOK',
//       },
//     ],
//   },
// }

has()​

The has method determines if one or more keys exists in the collection:

const collection = new Collection({
  animal: 'unicorn',
  ability: 'magical',
})

collection.has('ability')

// true

collection.has(['animal', 'ability'])

// true

collection.has(['animal', 'ability', 'name'])

// false

implode()​

The implode method joins the items in a collection. Its arguments depend on the type of items in the collection. If the collection contains arrays or objects, you should pass the key of the attributes you wish to join, and the "glue" string you wish to place between the values:

const collection = new Collection([
  {
    product: 'Chair',
    manufacturer: 'IKEA',
  },
  {
    product: 'Desk',
    manufacturer: 'IKEA',
  },
  {
    product: 'Chair',
    manufacturer: 'Herman Miller',
  },
])

collection.implode('product', ',')

// Chair, Desk, Chair

If the collection contains simple strings or numeric values, simply pass the "glue" as the only argument to the method:

new Collection([1, 2, 3, 4, 5]).implode('-')

// 1-2-3-4-5

intersect()​

The intersect method removes any values from the original collection that are not present in the given array or collection. The resulting collection will preserve the original collection's keys:

const collection = new Collection([1, 2, 3, 4, 5])

intersect = collection.intersect([1, 2, 3, 9])

intersect.all()

// [1, 2, 3]

intersectByKeys()​

The intersectByKeys method removes any keys from the original collection that are not present in the given array or collection:

const collection = new Collection({
  serial: 'UX301',
  type: 'screen',
  year: 2009,
})

const intersect = collection.intersectByKeys({
  reference: 'UX404',
  type: 'tab',
  year: 2011,
})

intersect.all()

// { type: 'screen', year: 2009 }
const firstCollection = new Collection([1, 2, 3, 4, 5])
const secondCollection = new Collection([1, 2, 3, 9])

intersect = firstCollection.intersect(secondCollection)

intersect.all()

// [1, 2, 3]

isEmpty()​

The isEmpty method returns true if the collection is empty otherwise, false is returned:

new Collection().isEmpty()
// true

new Collection([]).isEmpty()
// true

new Collection({}).isEmpty()
// true

isNotEmpty()​

The isNotEmpty method returns true if the collection is not empty otherwise, false is returned:

new Collection([1, 2, 3]).isNotEmpty()
//  true

new Collection().isNotEmpty()
// false

new Collection([]).isNotEmpty()
// false

new Collection({}).isNotEmpty()
// false

join()​

The join method joins the collection's values with a string:

new Collection(['a', 'b', 'c']).join(', ')
// 'a, b, c'

new Collection(['a', 'b', 'c']).join(', ', ', and ')
// 'a, b, and c'

new Collection(['a', 'b']).join(', ', ' and ')
// 'a and b'

new Collection(['a']).join(', ', ' and ')
// 'a'

new Collection([]).join(', ', ' and ')
// ''

keyBy()​

The keyBy method keys the collection by the given key. If multiple items have the same key, only the last one will appear in the new collection:

const collection = new Collection([
  {
    product: 'Chair',
    manufacturer: 'IKEA',
  },
  {
    product: 'Desk',
    manufacturer: 'IKEA',
  },
  {
    product: 'Chair',
    manufacturer: 'Herman Miller',
  },
])

const keyed = collection.keyBy('manufacturer')

keyed.all()

// {
//   IKEA: {
//     product: 'Desk',
//     manufacturer: 'IKEA',
//   },
//   'Herman Miller': {
//     product: 'Chair',
//     manufacturer: 'Herman Miller',
//   },
// }

You may also pass a callback to the method. The callback should return the value to key the collection by:

const upperCased = collection.keyBy(item => item.manufacturer.toUpperCase())

upperCased.all()

// {
//   IKEA: {
//     product: 'Desk',
//     manufacturer: 'IKEA',
//   },
//   'HERMAN MILLER': {
//     product: 'Chair',
//     manufacturer: 'Herman Miller',
//   },
// }

keys()​

The keys method returns all of the collection's keys:

const collection = new Collection([
  {
    club: 'Liverpool',
    nickname: 'The Reds',
  },
])

keys = collection.keys()

// ['club', 'nickname']

last()​

The last method returns the last element in the collection that passes a given truth test:

const collection = new Collection([1, 2, 3])

const last = collection.last(item => item > 1)

// 3

You may also call the last method with no arguments to get the last element in the collection. If the collection is empty, null is returned:

new Collection([1, 2, 3, 4]).last()

// 4

macro()​

The macro method lets you register custom methods

new Collection().macro('uppercase', function () {
  return this.map(item => item.toUpperCase())
})

const collection = new Collection(['a', 'b', 'c'])

collection.uppercase()

collection.all()

// ['A', 'B', 'C']

Note that the macro method returns undefined, and therefore it is not possible to use it within a chain of methods.

make()​

The make method creates a new collection instance.

map()​

The map method iterates through the collection and passes each value to the given callback. The callback is free to modify the item and return it, thus forming a new collection of modified items:

const collection = new Collection([1, 2, 3, 4, 5])

const multiplied = collection.map(item => item * 2)

multiplied.all()

// [2, 4, 6, 8, 10]

Like most other collection methods, map returns a new collection instance it does not modify the collection it is called on. If you want to transform the original collection, use the transform method.

mapInto()​

The mapInto method iterates through the collection and instantiates the given class with each element as a constructor:

const Player = function (name) {
  this.name = name
}

const collection = new Collection([
  'Roberto Firmino',
  'Darwin Núñez',
])

const players = collection.mapInto(Player)

players.all()

// [
//   Player { name: 'Roberto Firmino' },
//   Player { name: 'Darwin Núñez' },
// ]

mapSpread()​

The mapSpread method iterates over the collection's items, passing each nested item value into the given callback. The callback is free to modify the item and return it, thus forming a new collection of modified items:

const collection = new Collection([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

const chunks = collection.chunk(2)

const sequence = chunks.mapSpread((even, odd) => even + odd)

sequence.all()

// [1, 5, 9, 13, 17]

mapToDictionary()​

Run a dictionary map over the items. The callback should return an associative array with a single key/value pair.

const collection = new Collection([
  { id: 1, name: 'a' },
  { id: 2, name: 'b' },
  { id: 3, name: 'c' },
  { id: 4, name: 'b' },
])

const groups = collection.mapToDictionary(item => [item.name, item.id])

groups.all()

// {
//   a: [1],
//   b: [2, 4],
//   c: [3],
// }

mapToGroups()​

The mapToGroups method iterates through the collection and passes each value to the given callback:

const collection = new Collection([
  { id: 1, name: 'A' },
  { id: 2, name: 'B' },
  { id: 3, name: 'C' },
  { id: 4, name: 'B' },
])

const groups = collection.mapToGroups((item, key) => [item.name, item.id])

// {
//   A: [1],
//   B: [2, 4],
//   C: [3],
// }

mapWithKeys()​

The mapWithKeys method iterates through the collection and passes each value to the given callback. The callback should return an array where the first element represents the key and the second element represents the value pair:

const collection = new Collection([
  {
    name: 'John',
    department: 'Sales',
    email: 'john@example.com',
  },
  {
    name: 'Jane',
    department: 'Marketing',
    email: 'jane@example.com',
  },
])

const keyed = collection.mapWithKeys(item => [item.email, item.name])

keyed.all()

// {
//   'john@example.com': 'John',
//   'jane@example.com': 'Jane',
// }

max()​

The max method returns the maximum value of a given key:

const collection = new Collection([
  {
    value: 10,
  },
  {
    value: -13,
  },
  {
    value: 12,
  },
  {
    unicorn: false,
  },
])

const max = collection.max('value')

// 12
new Collection([-1, -2345, 12, 11, 3]).max()

// 12

median()​

The median method returns the median value of a given key:

new Collection([1, 3, 3, 6, 7, 8, 9]).median()

// 6
new Collection([
  {
    foo: 1,
  },
  {
    foo: 1,
  },
  {
    foo: 2,
  },
  {
    foo: 4,
  },
]).median('foo')

// 1.5

merge()​

The merge method merges the given object into the original collection. If a key in the given object matches a key in the original collection, the given objects value will overwrite the value in the original collection:

const collection = new Collection({
  id: 1,
  price: 29,
})

const merged = collection.merge({
  price: 400,
  discount: false,
})

merged.all()

// { id: 1, price: 400, discount: false }

If our collection is an array, the values will be appended to the end of the collection:

const collection = new Collection(['Unicorn', 'Rainbow'])

const merged = collection.merge(['Sunshine', 'Rainbow'])

merged.all()

// ['Unicorn', 'Rainbow', 'Sunshine', 'Rainbow']

mergeRecursive()​

The mergeRecursive method merges the given array or collection recursively with the original collection. If a string key in the given items matches a string key in the original collection, then the values for these keys are merged together into an array, and this is done recursively:

const collection = new Collection({
  product_id: 1,
  price: 100,
})

const merged = collection.mergeRecursive({
  product_id: 2,
  price: 200,
  discount: false,
})

merged.all()

// {
//   product_id: [1, 2],
//   price: [100, 200],
//   discount: false,
// }

min()​

The min method returns the minimum value of a given key:

const collection = new Collection([
  {
    worth: 100,
  },
  {
    worth: 900,
  },
  {
    worth: 79,
  },
])

collection.min('worth')

// 79
new Collection([1, 2, 3, 4, 5]).min()

// 1

mode()​

The mode method returns the mode value of a given key:

new Collection([1, 3, 3, 6, 7, 8, 9]).mode()

// [3]
new Collection([
  {
    foo: 1,
  },
  {
    foo: 1,
  },
  {
    foo: 2,
  },
  {
    foo: 4,
  },
]).mode('foo')

// [1]

nth()​

The nth method creates a new collection consisting of every n-th element:

const collection = new Collection(['a', 'b', 'c', 'd', 'e', 'f'])

const nth = collection.nth(4)

nth.all()

// ['a', 'e']

only()​

The only method returns the items in the collection with the specified keys:

const collection = new Collection({
  id: 12,
  name: 'John Doe',
  email: 'john@doe.com',
  active: true,
})

const filtered = collection.only(['name', 'email'])

filtered.all()

// { name: 'John Doe', email: 'john@doe.com' }
new Collection([1, 2, 3, 4])
  .only([2, 12])
  .all()

// [2]

For the inverse of only, see the except method.

order()​

Alias for the sort method.

orderDesc()​

Alias for the sortDesc method.

orderBy()​

Alias for the sortBy method.

orderByDesc()​

Alias for the sortByDesc method.

orderKeys()​

Alias for the sortKeys method.

orderKeysDesc()​

Alias for the sortKeysDesc method.

pad()​

The pad method will fill the array with the given value until the array reaches the specified size. This method behaves like the array_pad PHP function.

To pad to the left, you should specify a negative size. No padding will take place if the absolute value of the given size is less than or equal to the length of the array:

const collection = new Collection(['A', 'B', 'C'])

let filtered = collection.pad(5, 0)

filtered.all()

// ['A', 'B', 'C', 0, 0]

filtered = collection.pad(-5, 0)

filtered.all()

// [0, 0, 'A', 'B', 'C']

partition()​

The partition method may be combined with destructuring to separate elements that pass a given truth test from those that do not:

const collection = new Collection([1, 2, 3, 4, 5, 6])

const [underThree, overThree] = collection.partition(i => i < 3)

pipe()​

The pipe method passes the collection to the given callback and returns the result:

const collection = new Collection([1, 2, 3])

const piped = collection.pipe(items => items.sum())

// 6

pluck()​

The pluck method retrieves all of the values for a given key:

const collection = new Collection([
  {
    id: 78,
    name: 'Aeron',
  },
  {
    id: 79,
    name: 'Embody',
  },
])

const plucked = collection.pluck('name')

plucked.all()

// ['Aeron', 'Embody']

You may also specify how you wish the resulting collection to be keyed:

const collection = new Collection([
  {
    id: 78,
    name: 'Aeron',
  },
  {
    id: 79,
    name: 'Embody',
  },
])

const plucked = collection.pluck('name', 'id')

plucked.all()

// {
//   78: 'Aeron',
//   79: 'Embody',
// }

You can use "dot notation" to access nested values

const collection = new Collection([
  {
    name: 'John',
    roles: [
      {
        name: 'Editor',
      },
      {
        name: 'Admin',
      },
    ],
  },
])

const plucked = collection.pluck('roles.0.name')

plucked.all()

// ['Editor']

"Dot notation" supports "wildcard"

const collection = new Collection([
  {
    name: 'John',
    roles: [
      {
        name: 'Editor',
      },
      {
        name: 'Admin',
      },
    ],
  },
])

const plucked = collection.pluck('roles.*.name')

plucked.all()

// [
//   [
//     'Editor',
//     'Admin',
//   ],
// ]

pop()​

The pop method removes and returns the last item from the collection:

const collection = new Collection([1, 2, 3, 4, 5])

collection.pop()

// 5

collection.all()

// => [1, 2, 3, 4]

You may provide number of items to pop. This will return the popped items in a new collection:

const collection = new Collection([1, 2, 3, 4, 5])

collection.pop(2).all()

// [4, 5]

collection.all()

// => [1, 2, 3]

prepend()​

The prepend method adds an item to the beginning of the collection:

const collection = new Collection([1, 2, 3, 4, 5])

collection.prepend(0)

collection.all()

// [0, 1, 2, 3, 4, 5]

You may also pass a second argument to set the key of the prepended item:

tip

Order of properties in objects is not guaranteed in JavaScript When calling prepend with a key, the Collection uses the underlying put method behind the scenes.

const collection = new Collection({
  product: 'iPhone 6s',
})

collection.prepend('Apple', 'brand')

collection.all()

// {
//   brand: 'Apple',
//   product: 'iPhone 6s',
// }

pull()​

The pull method removes and returns an item from the collection by its key:

const collection = new Collection({
  firstname: 'Michael',
  lastname: 'Cera',
})

collection.pull('lastname')

// Cera

collection.all()

// { firstname: 'Michael' }

push()​

The push method appends an item to the end of the collection:

const collection = new Collection([1, 2, 3, 4])

collection.push(5)

collection.all()

// [1, 2, 3, 4, 5]

put()​

The put method sets the given key and value in the collection:

const collection = new Collection(['JavaScript', 'Python'])

collection.put('Ruby')

collection.all()

// ['JavaScript', 'Python', 'Ruby']

random()​

The random method returns a random item from the collection:

const collection = new Collection([1, 2, 3, 4, 5])

collection.random()

// 4 (retrieved randomly)

You may optionally pass an integer to random to specify how many items you would like to randomly retrieve. A collection of items is always returned when explicitly passing the number of items you wish to receive:

const threeRandom = collection.random(3)

// Collection { items: [ 5, 3, 4 ] } (retrieved randomly)

const oneRandom = collection.random(1)

// Collection { items: [ 3 ] } (retrieved randomly)

oneRandom.all()

// [3]

reduce()​

The reduce method reduces the collection to a single value, passing the result of each iteration into the subsequent iteration:

const collection = new Collection([1, 2, 3])

const total = collection.reduce((carry, item) => carry + item)

// 6

The value for carry on the first iteration is null however, you may specify its initial value by passing a second argument to reduce:

const total = collection.reduce((carry, item) => carry + item, 4)

// 10

reject()​

The reject method filters the collection using the given callback. The callback should return true if the item should be removed from the resulting collection:

const collection = new Collection([1, 2, 3, 4])

const filtered = collection.reject(value => value > 2)

// [1, 2]

For the inverse of the reject method, see the filter method.

removeDuplicated()​

The removeDuplicated method remove all duplicated values inside the collection:

const collection = new Collection([1, 1, 2, 2, 3, 4])

const set = collection.removeDuplicated()

// [1, 2, 3, 4]

replace()​

The replace method behaves similarly to merge however, in addition to overwriting matching items with string keys, the replace method will also overwrite items in the collection that have matching numeric keys:

const collection = new Collection({
  name: 'Bob',
})

const replaced = collection.replace({
  name: 'John',
  number: 45,
})

replaced.all()

// {
//   name: 'John',
//   number: 45,
// }

replaceRecursive()​

This method works like replace, but it will recurse into arrays and apply the same replacement process to the inner values:

const collection = new Collection([
  'Matip',
  'van Dijk',
  [
    'Núñez',
    'Firmino',
    'Salah',
  ],
])

const replaced = collection.replaceRecursive({
  0: 'Gomez',
  2: { 1: 'Origi' },
})

replaced.all()

// {
//   0: 'Gomez',
//   1: 'van Dijk',
//   2: { 0: 'Núñez', 1: 'Origi', 2: 'Salah' },
// }

reverse()​

The reverse method reverses the order of the collection's items:

const collection = new Collection([1, 2, 3, 4, 5])

const reversed = collection.reverse()

reversed.all()

// [5, 4, 3, 2, 1]

The search method searches the collection for the given value and returns its key if found. If the item is not found, false is returned.

const collection = new Collection([2, 4, 6, 8])

collection.search(4)

// 1

The search is done using a "loose" comparison, meaning a string with an integer value will be considered equal to an integer of the same value. To use strict comparison, pass true as the second argument to the method:

collection.search('4', true)

// false

Alternatively, you may pass in your own callback to search for the first item that passes your truth test:

collection.search((item, key) => item > 5)

// 2

shift()​

The shift method removes and returns the first item from the collection:

const collection = new Collection([1, 2, 3, 4, 5])

collection.shift()

// 1

collection.all()

// [2, 3, 4, 5]

You may provide number of items to shift. This will return the shifted items in a new collection:

const collection = new Collection([1, 2, 3, 4, 5])

collection.shift(2).all()

// [1, 2]

collection.all()

// => [3, 4, 5]

shuffle()​

The shuffle method randomly shuffles the items in the collection:

const collection = new Collection([1, 2, 3, 4, 5])

const shuffled = collection.shuffle()

shuffled.all()

// [3, 5, 1, 2, 4] (generated randomly)

skip()​

The skip method returns a new collection, without the first given amount of items:

const collection = new Collection([1, 2, 3, 4, 5, 6])

collection.skip(4).all()

// [5, 6]
const collection = new Collection({
  first: 'first',
  second: 'second',
  third: 'third',
  fourth: 'fourth',
  fifth: 'fifth',
})

collection.skip(4).all()

// { fifth: 'fifth' }

skipUntil()​

The skipUntil method skips items until the given callback returns true and then returns the remaining items in the collection:

const collection = new Collection([1, 2, 3, 4])

const subset = collection.skipUntil(item => item >= 3)

subset.all()

// [3, 4]

You may also pass a simple value to the skipUntil method to skip all items until the given value is found:

const collection = new Collection([1, 2, 3, 4])

const subset = collection.skipUntil(3)

subset.all()

// [3, 4]

skipWhile()​

The skipWhile method skips items while the given callback returns true and then returns the remaining items in the collection:

const collection = new Collection([1, 2, 3, 4])

const subset = collection.skipWhile(item => item <= 3)

subset.all()

// [4]

If the callback never returns true, the skipWhile method will return an empty collection.

You may also pass a simple value to the skipWhile:

const collection = new Collection([1, 1, 2, 2, 3, 3, 4, 4])

const subset = collection.skipWhile(1)

subset.all()

// [2, 2, 3, 3, 4, 4]

slice()​

The slice method returns a slice of the collection starting at the given index:

const collection = new Collection([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])

const slice = collection.slice(4)

slice.all()

// [5, 6, 7, 8, 9, 10]

If you would like to limit the size of the returned slice, pass the desired size as the second argument to the method:

const slice = collection.slice(4, 2)

slice.all()

// [5, 6]

sole()​

The sole method returns the first element in the collection that passes a given truth test, but only if the truth test matches exactly one element:

new Collection([1, 2, 3, 4]).sole(item => item === 1)

// 1

If there are no elements in the collection that should be returned by the sole method, then an error will be thrown:

new Collection([1, 2, 3, 4]).sole(item => item > 4)

// Error ('Item not found.') is thrown.

If there are multiple elements in the collection that should be returned by the sole method, then an error will be thrown:

new Collection([1, 2, 3, 4]).sole()

// Error ('Multiple items found.') is thrown.

Like the firstOrFail method, you may also pass an attribute, operator, and value:

const collection = new Collection([
  { product: 'Desk', price: 200, discounted: true },
  { product: 'Chair', price: 100, discounted: true },
  { product: 'Bookcase', price: 150, discounted: true },
  { product: 'Door', price: 100 },
])

collection.sole('product', '=', 'Desk')

// { product: 'Desk', price: 200, discounted: true }

some()​

Alias for the contains method.

sort()​

The sort method sorts the collection:

const collection = new Collection([5, 3, 1, 2, 4])

const sorted = collection.sort()

sorted.all()

// [1, 2, 3, 4, 5]

If your sorting needs are more advanced, you may pass a callback to sort with your own algorithm.

const collection = new Collection([5, 3, 1, 2, 4])

const sorted = collection.sort((a, b) => b - a)

sorted.all()

// [5, 4, 3, 2, 1]

If you need to sort a collection of nested arrays or objects, see the sortBy and sortByDesc methods.

sortBy()​

The sortBy method sorts the collection by the given key. The sorted collection keeps the original array keys, so in this example we'll use the values method to reset the keys to consecutively numbered indexes:

const collection = new Collection([
  { name: 'Desk', price: 200 },
  { name: 'Chair', price: 100 },
  { name: 'Bookcase', price: 150 },
])

const sorted = collection.sortBy('price')

sorted.all()

// [
//   { name: 'Chair', price: 100 },
//   { name: 'Bookcase', price: 150 },
//   { name: 'Desk', price: 200 },
// ]

You can use dot notation to sort by nested values

const collection = new Collection([
  {
    name: 'Desk',
    price: 200,
    manufacturer: {
      name: 'IKEA',
    },
  },
  {
    name: 'Chair',
    price: 100,
    manufacturer: {
      name: 'Herman Miller',
    },
  },
  {
    name: 'Bookcase',
    price: 150,
    manufacturer: {
      name: 'IKEA',
    },
  },
])

const sorted = collection.sortBy('manufacturer.name')

sorted.all()

// [
//   {
//     name: 'Chair',
//     price: 100,
//     manufacturer: {
//       name: 'Herman Miller',
//     },
//   },
//   {
//     name: 'Desk',
//     price: 200,
//     manufacturer: {
//       name: 'IKEA',
//     },
//   },
//   {
//     name: 'Bookcase',
//     price: 150,
//     manufacturer: {
//       name: 'IKEA',
//     },
//   },
// ]

You can also pass your own callback to determine how to sort the collection values:

const collection = new Collection([
  { name: 'Desk', colors: ['Black', 'Mahogany'] },
  { name: 'Chair', colors: ['Black'] },
  { name: 'Bookcase', colors: ['Red', 'Beige', 'Brown'] },
])

const sorted = collection.sortBy((product, key) => product.colors.length)

sorted.all()

// [
//   { name: 'Chair', colors: ['Black'] },
//   { name: 'Desk', colors: ['Black', 'Mahogany'] },
//   { name: 'Bookcase', colors: ['Red', 'Beige', 'Brown'] },
// ]

sortByDesc()​

This method has the same signature as the sortBy method, but will sort the collection in the opposite order.

sortDesc()​

This method will sort the collection in the opposite order as the sort method.

const collection = new Collection([1, 3, 5, 2, 4])

const sorted = collection.sortDesc()

sorted.all()

// [5, 4, 3, 2, 1]

Unlike sort, you may not pass a callback to sortDesc. If you wish to use a callback, you should use sort and invert your comparison.

sortKeys()​

The sortKeys method sorts the collection by the keys of the underlying associative array:

const collection = new Collection({
  id: 10,
  first: 'Darwin',
  last: 'Núñez',
})

const sorted = collection.sortKeys()

sorted.all()

// {
//   first: 'Darwin',
//   id: 10,
//   last: 'Núñez',
// }

sortKeysDesc()​

This method has the same signature as the sortKeys method, but will sort the collection in the opposite order.

splice()​

The splice method removes and returns a slice of items starting at the specified index:

const collection = new Collection([1, 2, 3, 4, 5])

const chunk = collection.splice(2)

chunk.all()

// [3, 4, 5]

collection.all()

// [1, 2]

You may pass a second argument to limit the size of the resulting chunk:

const collection = new Collection([1, 2, 3, 4, 5])

const chunk = collection.splice(2, 1)

chunk.all()

// [3]

collection.all()

// [1, 2, 4, 5]

In addition, you can pass a third argument containing the new items to replace the items removed from the collection:

const collection = new Collection([1, 2, 3, 4, 5])

const chunk = collection.splice(2, 1, [10, 11])

chunk.all()

// [3]

collection.all()

// [1, 2, 10, 11, 4, 5]

split()​

The split method breaks a collection into the given number of groups:

const collection = new Collection([1, 2, 3, 4, 5])

const groups = collection.split(3)

// [[1, 2], [3, 4], [5]]

sum()​

The sum method returns the sum of all items in the collection:

new Collection([1, 2, 3]).sum()

// 6

If the collection contains nested arrays or objects, you should pass a key to use for determining which values to sum:

const collection = new Collection([
  { name: 'My story', pages: 176 },
  { name: 'Fantastic Beasts and Where to Find Them', pages: 1096 },
])

collection.sum('pages')

// 1272

In addition, you may pass your own callback to determine which values of the collection to sum:

const collection = new Collection([
  { name: 'Desk', colors: ['Black', 'Mahogany'] },
  { name: 'Chair', colors: ['Black'] },
  { name: 'Bookcase', colors: ['Red', 'Beige', 'Brown'] },
])

const total = collection.sum(product => product.colors.length)

// 6

take()​

The take method returns a new collection with the specified number of items: You may also pass a negative integer to take the specified amount of items from the end of the collection:

const collection = new Collection([0, 1, 2, 3, 4, 5])

const chunk = collection.take(3)

chunk.all()

// [0, 1, 2]

takeUntil()​

The takeUntil method returns items in the collection until the given callback returns true:

const collection = new Collection([1, 2, 3, 4])

const subset = collection.takeUntil(item => item >= 3)

subset.all()

// [1, 2]

If the given value is not found or the callback never returns true, the takeUntil method will return all items in the collection.

You may also pass a simple value to the takeUntil method to get the items until the given value is found:

const collection = new Collection([1, 2, 3, 4])

const subset = collection.takeUntil(3)

subset.all()

// [1, 2]

takeWhile()​

The takeWhile method returns items in the collection until the given callback returns false:

const collection = new Collection([1, 2, 3, 4])

const subset = collection.takeWhile(item => item < 3)

subset.all()

// [1, 2]

If the callback never returns false, the takeWhile method will return all items in the collection.

tap()​

The tap method passes the collection to the given callback, allowing you to "tap" into the collection at a specific point and do something with the items while not affecting the collection itself:

new Collection([2, 4, 3, 1, 5])
  .sort()
  .tap((collection) => {
    console.log(collection.all())

    // [1, 2, 3, 4, 5]
  })
  .shift()

// 1

times()​

The times method creates a new collection by invoking the callback a given amount of times:

const collection = new Collection().times(10, number => number * 9)

collection.all()

// [9, 18, 27, 36, 45, 54, 63, 72, 81, 90]

toArray()​

The toArray method converts the collection into a plain array. If the collection is an object, an array containing the values will be returned.

const collection = new Collection([1, 2, 3, 'b', 'c'])

collection.toArray()

// [1, 2, 3, 'b', 'c']
const collection = new Collection({
  name: 'Elon Musk',
  companies: ['Tesla', 'Space X', 'SolarCity'],
})

collection.toArray()

// ['Elon Musk', ['Tesla', 'Space X', 'SolarCity']]

toJson()​

The toJson method converts the collection into JSON string:

const collection = new Collection({
  id: 384,
  name: 'Rayquaza',
  gender: 'NA',
})

const json = collection.toJson()

// {"id": 384, "name": "Rayquaza", "gender": "NA"}

toJSON()​

Enter in all the collection objects and execute the toJSON() method of each object:

const collection = new Collection([
    { toJSON: () => ({ id: 1 }) }
])

const json = collection.toJSON()

// [{ id: 1 }]

toResource()​

Enter in all the collection objects and execute the toResource() method of each object:

const collection = new Collection([
    { toResource: criterias => ({ id: 1, ...criterias }) }
])

const resources = collection.toResource({ name: 'string' })

// [{ id: 1, name: 'string' }]

transform()​

The transform method iterates over the collection and calls the given callback with each item in the collection. The items in the collection will be replaced by the values returned by the callback:

const collection = new Collection([1, 2, 3, 4, 5])

collection.transform((item, key) => item * 2)

collection.all()

// [2, 4, 6, 8, 10]

Unlike most other collection methods, transform modifies the collection itself. If you wish to create a new collection instead, use the map method.

undot()​

The undot method expands a single-dimensional collection that uses "dot" notation into a multi-dimensional collection:

const person = new Collection({
  'name.first_name': 'Marie',
  'name.last_name': 'Valentine',
  'address.line_1': '2992 Eagle Drive',
  'address.line_2': '',
  'address.suburb': 'Detroit',
  'address.state': 'MI',
  'address.postcode': '48219',
})

const undotted = person.undot()

const all = undotted.all()

// {
//   name: {
//       first_name: 'Marie',
//       last_name: 'Valentine',
//   },
//   address: {
//       line_1: '2992 Eagle Drive',
//       line_2: '',
//       suburb: 'Detroit',
//       state: 'MI',
//       postcode: '48219',
//   },
// }

union()​

The union method adds the given array to the collection. If the given array contains keys that are already in the original collection, the original collection's values will be preferred:

const collection = new Collection({
  a: 'A',
  b: 'B',
})

const union = collection.union({
  a: 'AAA',
  c: 'CCC',
  b: 'BBB',
})

union.all()

// {
//   a: 'A',
//   b: 'B',
//   c: 'CCC',
// }

unique()​

The unique method returns all of the unique items in the collection:

const collection = new Collection([1, 1, 1, 2, 3, 3])

const unique = collection.unique()

unique.all()

// [1, 2, 3]

When dealing with an array of objects, you may specify the key used to determine uniqueness:

const collection = new Collection([
  { name: 'iPhone 6', brand: 'Apple', type: 'phone' },
  { name: 'iPhone 5', brand: 'Apple', type: 'phone' },
  { name: 'Apple Watch', brand: 'Apple', type: 'watch' },
  { name: 'Galaxy S6', brand: 'Samsung', type: 'phone' },
  { name: 'Galaxy Gear', brand: 'Samsung', type: 'watch' },
])

const unique = collection.unique('brand')

unique.all()

// [
//   { name: 'iPhone 6', brand: 'Apple', type: 'phone' },
//   { name: 'Galaxy S6', brand: 'Samsung', type: 'phone' },
// ]

You may also pass your own callback to determine item uniqueness:

const collection = new Collection([
  { name: 'iPhone 6', brand: 'Apple', type: 'phone' },
  { name: 'iPhone 5', brand: 'Apple', type: 'phone' },
  { name: 'Apple Watch', brand: 'Apple', type: 'watch' },
  { name: 'Galaxy S6', brand: 'Samsung', type: 'phone' },
  { name: 'Galaxy Gear', brand: 'Samsung', type: 'watch' },
])

const unique = collection.unique(item => item.brand + item.type)

unique.all()

// [
//   { name: 'iPhone 6', brand: 'Apple', type: 'phone' },
//   { name: 'Apple Watch', brand: 'Apple', type: 'watch' },
//   { name: 'Galaxy S6', brand: 'Samsung', type: 'phone' },
//   { name: 'Galaxy Gear', brand: 'Samsung', type: 'watch' },
// ]

unless()​

The unless method will execute the given callback when the first argument given to the method evaluates to false:

const collection = new Collection([1, 2, 3])

collection.unless(false, items => items.push(4))

collection.all()

// [1, 2, 3, 4]

unlessEmpty()​

Alias for the whenNotEmpty() method

unlessNotEmpty()​

Alias for the whenEmpty() method

unwrap()​

The unwrap method will unwrap the given collection:

const collection = new Collection([1, 2, 3])

new Collection().unwrap(collection)

// [1, 2, 3]

values()​

The values method returns a new collection with the keys reset to consecutive integers:

const collection = new Collection({
  a: 'xoxo',
  b: 'abab',
  c: '1337',
  1337: 12,
})

const values = collection.values()

values.all()

// [12, 'xoxo', 'abab', '1337']

when()​

The when method will execute the given callback when the first argument given to the method evaluates to true:

const collection = new Collection([1, 2, 3])

collection.when(true, items => items.push(4))

collection.all()

// [1, 2, 3, 4]

whenEmpty()​

The whenEmpty method will execute the given callback when the collection is empty:

const collection = new Collection([])

collection.whenEmpty(c => c.push('Mohamed Salah'))

collection.all()

// ['Mohamed Salah']
const collection = new Collection(['Darwin Núñez'])

collection.whenEmpty(
  c => c.push('Mohamed Salah'),
  c => c.push('Xherdan Shaqiri'),
)

collection.all()

// [
//   'Darwin Núñez',
//   'Xherdan Shaqiri',
// ]

whenNotEmpty()​

The whenNotEmpty method will execute the given callback when the collection is not empty:

const collection = new Collection(['Darwin Núñez'])

collection.whenNotEmpty(c => c.push('Mohamed Salah'))

collection.all()

// [
//   'Darwin Núñez',
//   'Mohamed Salah',
// ]
const collection = new Collection(['Darwin Núñez'])

collection.whenNotEmpty(
  c => c.push('Mohamed Salah'),
  c => c.push('Xherdan Shaqiri'),
)

collection.all()

// [
//   'Darwin Núñez',
//   'Mohamed Salah',
// ]

where()​

The where method filters the collection by a given key / value pair:

const collection = new Collection([
  { product: 'Desk', price: 200, discounted: true },
  { product: 'Chair', price: 100, discounted: true },
  { product: 'Bookcase', price: 150, discounted: true },
  { product: 'Door', price: 100 },
])

const filtered = collection.where('price', 100)

filtered.all()

// [
//   { product: 'Chair', price: 100 },
//   { product: 'Door', price: 100 },
// ]

const discounted = collection.where('discounted')

discounted.all()

// [
//  { product: 'Desk', price: 200, discounted: true },
//  { product: 'Chair', price: 100, discounted: true },
//  { product: 'Bookcase', price: 150, discounted: true },
// ]

const notDiscounted = collection.where('discounted', false)

discounted.all()

// [
//  { product: 'Door', price: 100 },
// ]

When working with nested objects where() method allows dot notated keys. E.g. where('product.category', 'office-supplies') The where method also allows for custom comparisons:

Non-identity / strict inequality (!==)

const filtered = collection.where('price', '!==', 100)

filtered.all()

// [
//   { product: 'Desk', price: 200 },
//   { product: 'Bookcase', price: 150 },
// ]

Less than operator (<)

const filtered = collection.where('price', '<', 100)

filtered.all()

// []

Less than or equal operator (<=)

const filtered = collection.where('price', '<=', 100)

filtered.all()

// [
//   { product: 'Chair', price: 100 },
//   { product: 'Door', price: 100 },
// ]

Greater than operator (>)

const filtered = collection.where('price', '>', 100)

filtered.all()

// [
//   { product: 'Desk', price: 200} ,
//   { product: 'Bookcase', price: 150 },
// ]

Greater than or equal operator (>=)

const filtered = collection.where('price', '>=', 150)

filtered.all()

// [
//   { product: 'Desk', price: 200} ,
//   { product: 'Bookcase', price: 150 },
// ]

whereBetween()​

The whereBetween method filters the collection within a given range:

const collection = new Collection([
  { product: 'Desk', price: 200 },
  { product: 'Chair', price: 80 },
  { product: 'Bookcase', price: 150 },
  { product: 'Pencil', price: 30 },
  { product: 'Door', price: 100 },
])

const filtered = collection.whereBetween('price', [100, 200])

filtered.all()

// [
//   { product: 'Desk', price: 200 },
//   { product: 'Bookcase', price: 150 },
//   { product: 'Door', price: 100 },
// ]

whereIn()​

The whereIn method filters the collection by a given key / value contained within the given array.

const collection = new Collection([
  { product: 'Desk', price: 200 },
  { product: 'Chair', price: 100 },
  { product: 'Bookcase', price: 150 },
  { product: 'Door', price: 100 },
])

const filtered = collection.whereIn('price', [100, 150])

filtered.all()

// [
//   { product: 'Chair', price: 100 },
//   { product: 'Bookcase', price: 150 },
//   { product: 'Door', price: 100 },
// ]

When working with nested objects whereIn() method allows dot notated keys. E.g. whereIn('product.categories', ['office-supplies', 'furniture'])

whereInstanceOf()​

The whereInstanceOf method filters the collection by a given class type:

const collection = new Collection([
  new Player('Firmino'),
  new Player('Salah'),
  new Manager('Klopp'),
])

const filtered = collection.whereInstanceOf(Player)

filtered.all()

// [
//   new Player('Firmino'),
//   new Player('Salah'),
// ]

whereNotBetween()​

The whereNotBetween method filters the collection within a given range:

const collection = new Collection([
  { product: 'Desk', price: 200 },
  { product: 'Chair', price: 80 },
  { product: 'Bookcase', price: 150 },
  { product: 'Pencil', price: 30 },
  { product: 'Door', price: 100 },
])

const filtered = collection.whereNotBetween('price', [100, 200])

filtered.all()

// [
//   { product: 'Chair', price: 80 },
//   { product: 'Pencil', price: 30 },
// ]

whereNotIn()​

The whereNotIn method filters the collection by a given key / value not contained within the given array:

const collection = new Collection([
  { product: 'Desk', price: 200 },
  { product: 'Chair', price: 100 },
  { product: 'Bookcase', price: 150 },
  { product: 'Door', price: 100 },
])

const filtered = collection.whereNotIn('price', [150, 200])

filtered.all()

// [
//   { product: 'Chair', price: 100 },
//   { product: 'Door', price: 100 },
// ]

When working with nested objects whereNotIn() method allows dot notated keys. E.g. whereNotIn('product .categories', ['office-supplies', 'furniture'])

whereNotNull()​

The whereNotNull method filters items where the given key is not null.

const collection = new Collection([{
  name: 'Mohamed Salah',
}, {
  name: null,
}, {
  name: 'Darwin Núñez',
}])

const filtered = collection.whereNotNull()

filtered.all()

// [
//   { name: 'Mohamed Salah' },
//   { name: 'Darwin Núñez' },
// ]

whereNull()​

The whereNull method filters items where the given key is null.

const collection = new Collection([{
  name: 'Mohamed Salah',
}, {
  name: null,
}, {
  name: 'Darwin Núñez',
}])

const filtered = collection.whereNull()

filtered.all()

// [
//   { name: null },
// ]

wrap()​

The wrap method will wrap the given value in a collection:

const collection = new Collection().wrap([1, 2, 3])

collection.all()

// [1, 2, 3]

zip()​

The zip method merges together the values of the given array with the values of the original collection at the corresponding index:

const collection = new Collection(['Chair', 'Desk'])

const zipped = collection.zip([100, 200])

zipped.all()

// [['Chair', 100], ['Desk', 200]]