@baethon/collect

This package is supposed to be immutable, eventually consistent (let's say heavily inspired) clone of Laravel's support class for collections.

Deprecated

This package is not maintained anymore. I recommend switching to collect.js.

Installation

npm install --save @baethon/collect

Requirements

Package is compiled to ES5 so it can be used almost in every environment.
It may be required to install es5-shim.

Development

TSLint and Mocha unit tests:

npm test

Library compilation (compiled sources are not commited to repo):

npm run lib

Generate API docs:

npm run docs

Extending

Collection class is extendable via macro() static method.

import {Collection} from '@baethon/collect';

Collection.macro('even', () => {
  return this.filter(i => i % 2 === 0);
});

collect([1, 2, 3, 4]).even();
// Collection of [2, 4]

When macro returns non-arrayable value it will be simply returned.

import {Collection} from '@baethon/collect';

Collection.macro('countPlusTen', () => this.getAll().length + 10);

collect([1]).countPlusTen();
// 10

Functions

collect(items)

Creates new Collection instance

import {collect} from '@baethon/collect';

const collection = collect([1, 2, 3]);

Returns: Collection

Class: Collection

Collection.getAll()

Returns array/object stored inside Collection instance

Returns: any

Collection.keys()

Returns all of the collection keys

Returns: Collection

Collection.values()

Returns all values of collection

collect({name: 'Jon'}).values();
// Collection of ['Jon']

collect([1, 2, 3]).values();
// Collection of [1, 2, 3]

Returns: Collection

Collection.merge(items)

Merges the given array into the collection:

collect([1, 2, 3]).merge([4, 5, 6]);
// Collection of [1, 2, 3, 4, 5, 6]

Returns: Collection

Collection.forEach(callback)

Iterates over the items in the collection and passes each item to a given callback:

const collection = collect([1, 2, 3]).forEach(item => console.log(item));
// Collection of [1, 2, 3]

Returns: Collection

Collection.push(values)

Puts given values at the end of array

collect([1, 2, 3]).push(4, 5, 6);
// Collection of [1, 2, 3, 4, 5, 6]

Returns: Collection

Collection.map(callback)

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:

collect([1, 2, 3]).map(item => item + 1);
// Collection of [2, 3, 4]

Returns: Collection

Collection.filter(predicate)

Returns collections of items matching given predicate:

collect([1, 2, 3]).filter(i => i % 2 === 0);
// Collection of [2]

Returns: Collection

Collection.reject(predicate)

Returns collection of items not matching given predicate:

collect([1, 2, 3]).reject(i => i % 2 === 0);
// Collection of [1, 3]

Returns: Collection

Collection.avg(keyName)

Return average value of all items in collection

collect([1, 2, 3]).avg();
// 2

If the collection contains nested objects, keyName is required to use for determining which values to calculate the average:

const collection = collect([
  {name: 'JavaScript: The Good Parts', pages: 176},
  {name: 'JavaScript: The Definitive Guide', pages: 1096},
]);

collection.avg('pages');
// 636

Returns: number

Collection.collapse()

Collapse array of collections into flat collection

collect([[1, 2], [3, 4]]).collapse();
// Collection of [1, 2, 3, 4]

Collection.combine(values)

Combines the keys of the collection with the values of another array or collection

collect(['name', 'age']).combine(['Jon', 16]);
// Collection of { name: 'Jon', age: 16 }

Returns: Collection

Collection.pluck(valuesName, keyName)

Retrieves all of the collection values for a given key:

collect([{name: 'Jon'}, {name: 'Arya'}]).pluck('name');
// Collection of ['Jon', 'Arya']

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

collect([{name: 'Jon', house: 'Stark'}]).pluck('name', 'house');
// Collection of {Stark: 'Jon'}

Returns: Collection

Collection.contains(predicate, value)

Determines whether the collection contains a given item:

collect({name: 'Jon'}).contains('Jon');
// true

collect({name: 'Jon'}).contains('Arrya');
// false

It's possible to pass a key / value pair to the contains method, which will determine if the given pair exists in the collection:

const collection = collect([
  {name: 'Jon', lastname: 'Snow'},
  {name: 'Arya', lastname: 'Stark'},
]);

collection.contains('lastname', 'Stark');
// true

Also it's possible to pass own callback to perform truth test:

collection([1, 2, 3]).contains(i => i >= 3);
// true

Arguments passed to callback are the same as in Array.some method.

Returns: boolean

Collection.except(keys)

Returns all items in the collection except for those with the specified keys:

const collection = collect({productId: 1, name: 'Desk', price: 100, discount: false});
const filtered = collection.except(['price', 'discount']);
filtered.all();
// Collection of {productId: 1, name: 'Desk'}

Returns: Collection

Collection.flatMap(callback)

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 people = collect([
   {name: 'Jon', titles: ['King of the North', 'Knower of nothing']},
   {name: 'Arya', titles: ['Little assasin']}
]);

const titles = people.flatMap(person => person.titles);
// Collection of ['King of the North', 'Knower of nothing', 'Little assasin']

Returns: Collection

Collection.groupBy(key)

Groups the collection's items by a given key:

const collection = collect([
   { house: 'Stark', name: 'Jon' },
   { house: 'Stark', name: 'Arrya' },
]);

const byHouse = collection.groupBy('house');
// Collection of {
//   Stark: [
//     { house: 'Stark', name: 'Jon' },
//     { house: 'Stark', name: 'Arrya' },
//   ],
// }

In addition to passing a string key, it's possible to pass a callback. The callback should return the value you wish to key the group by:

const collection = collect([
   { house: 'Stark', name: 'Jon' },
   { house: 'Stark', name: 'Arrya' },
]);

const byHouse = collection.groupBy(person => person.house.toUpperCase());
// Collection of {
//   STARK: [
//     { house: 'Stark', name: 'Jon' },
//     { house: 'Stark', name: 'Arrya' },
//   ],
// }

Returns: Collection

Collection.has(key)

Determines if a given key exists in the collection:

collect({name: 'Jon'}).has('name');
// true

Collection.implode(key, glue)

Join the items in a collection.

Arguments depend on the type of items in the collection.

If the collection contains array of objects, you should pass the key of the attributes you wish to join, and the "glue" string you wish to place between the values:

collect([{name: 'Jon'}, {name: 'Arya'}]).implode('name', ', ');
// Jon, Arya

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

collect(['Jon', 'Arya']).implode(', ');
// Jon, Arya

Returns: string

Collection.keyBy(key)

Keys the collection by the given key:

let collection = collect([
   {productId: 'prod-100', name: 'desk'},
   {productId: 'prod-200', name: 'table'},
]);

collection.keyBy('productId');
// Collection of {
//   'prod-100': {productId: 'prod-100', name: 'desk'},
//   'prod-200': {productId: 'prod-200', name: 'table'},
// }

If multiple items have the same key, only the last one will appear in the new collection.

You may also pass your own callback, which should return the value to key the collection by:

collection.keyBy(item => item.productId.toUpperCase());
// Collection of {
//   'PROD-100': {productId: 'prod-100', name: 'desk'},
//   'PROD-200': {productId: 'prod-200', name: 'table'},
// }

Returns: Collection

Collection.prepend(value)

Add an item to the beginning of the collection

Returns: Collection

Collection.reduce(callback, carry)

Reduce the collection to a single value, passing the result of each iteration into the subsequent iteration:

collect([1, 2, 3]).reduce((carry, current) => {
   return carry ? carry + current : current;
});
// 6

The value for carry on the first iteration is null; however, its initial value can be specified by passing a second argument to reduce:

collect([1, 2, 3]).reduce((carry, current) => carry + current, 0);
// 6

Returns: any

Collection.sort(compareFunction)

Sort collection with given compareFunction.

collect([3, 5, 1]).sort((a, b) => b-a);
// Collection of [5, 3, 1]

If compareFunction is omitted, the array is sorted according to each character's Unicode code point value, according to the string conversion of each element.

collect([3,5,1]).sort();
// Collection of [1, 3, 5]

Returns: Collection

Collection.sortBy(key)

Sort the collection by the given key

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

const sorted = collection.sortBy('price');
// Collection of [
//    {name: 'Chair', price: 100},
//    {name: 'Bookcase', price: 150},
//    {name: 'Desk', price: 200},
// ]

Returns: Collection

Collection.sum(key)

Return the sum of all items in the collection:

collect([1, 2, 3]).sum();
// 6

If the collection contains nested objects, a key to use for determining which values to sum should be passed:

collect([
   {name: 'Desk', price: 200},
   {name: 'Chair', price: 100},
   {name: 'Bookcase', price: 150},
]).sum('price');
// 450

Returns: number

Collection.reverse()

Reverse the order of the collection's items:

collect([1, 2, 3]).revese();
// Collection of [3, 2, 1]

Returns: Collection

Collection.unique(key)

Return all of the unique items in the collection:

collect([1, 1, 2, 2, 3, 4, 2]).unique();
// Collection of [1, 2, 3, 4]

When dealing with nested objects, it's possible to specify the key used to determine uniqueness:

const collection = collect([
   {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'},
]);

collection.unique('brand');
// Collection of [
//   {name: 'iPhone 6', brand: 'Apple', type: 'phone'},
//   {name: 'Galaxy S6', brand: 'Samsung', type: 'phone'},
// ]

It's also possible to pass own callback to determine item uniqueness:

collection.unique(item => `${item.brand}${item.type}`);
// Collection of [
//   {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'},
// ]

Returns: Collection

Collection.where(key, value)

Filters the collection by a given key / value pair:

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

collection.where('price', 100);
// Collection of [
//   {product: 'Chair', price: 100},
//   {product: 'Door', price: 100},
// ]

Method uses strict comparisons when checking item values.

Returns: Collection

Collection.whereIn(key, values)

Filters the collection by a given key / value contained within the given array:

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

collection.whereIn('price', [100, 150]);
// Collection of [
//   {product: 'Chair', price: 100},
//   {product: 'Bookcase', price: 150},
//   {product: 'Door', price: 100},
// ]

Method uses strict comparisons when checking item values.

Returns: Collection

Collection.zip(items)

Merges together the values of the given array with the values of the collection at the corresponding index:

const collection = collect(['Chair', 'Desk']);
const zipped = collection.zip([100, 200]);
// Collection of [['Chair', 100], ['Desk', 200]]