Typescript Array Extensions

A library that adds common array higher order function support beyond the built in functions in js, e.g. map, filter, by extending the Array prototype.

Inspired by swift and LINQ.

Installing

npm i ts-array-extensions

Using

You can import all the functions

import 'ts-array-extensions';

or individual ones as you need them

import 'ts-array-extensions/compactMap';

Array.prototype extensions

• any
• compact
• compactMap
• compactMapAsync
• cume
• distinct
• except
• first
• forEachAsync
• groupBy
• innerJoin
• interleave
• leftJoin
• mapAsync
• max
• min
• none
• outerJoin
• sortBy
• sum
• toRecord
• union

any

Returns true if the array contains any elements.

[1, 2, 3].any();
// true

[].any();
// false

compact

Returns elements of the array that are not null or undefined.

[1, null, 2].compact();
// [1, 2]

compactMap

Maps elements and returns results that are not null or undefined.

[1, 2, 3].compactMap(v => {
  if (v % 2 !== 0) return v;
});
// [1, 3]

compactMapAsync

Same as compactMap but works with promises. Will await async callbacks.

await [1, 2, 3].compactMapAsync(async v => {
  await /* something */
  return v;
});
// [1, 2, 3]

cume

Returns the a running total of all the elements in the array, optionally mapping them first with a callback

[1, 10, 100].cume();
// [1, 11, 111]

[1, 10, 100].cume(v => v * 10);
// [10, 110, 1110]

distinct

Returns elements of the array that are unique, using a comparer function if supplied, or === if not.

[1, 1, 2, 2].distinct();
// [1, 2]

[
  { day: 1, month: 1, year: 1979 },
  { day: 1, month: 1, year: 1979 },
  { day: 2, month: 1, year: 1979 },
  { day: 2, month: 1, year: 1979 }
].distinct(
  (a, b) => a.day === b.day && a.month === b.month && a.year === b.year
);
// [
//   { day: 1, month: 1, year: 1979 },
//   { day: 2, month: 1, year: 1979 }
// ]

except

Returns values from the first array, that aren't present in the second, using a comparer function if supplied, or === if not.

[1, 2, 3].except([2, 3, 4]);
// [1]

[
  { day: 1, month: 1, year: 1979 },
  { day: 2, month: 1, year: 1979 }
].except(
  [
    { day: 2, month: 1, year: 1979 },
    { day: 3, month: 1, year: 1979 }
  ],
  (a, b) => a.day === b.day && a.month === b.month && a.year === b.year
);
// [
//   { day: 1, month: 1, year: 1979 }
// ]

first

Returns the first element of the array or null if empty.

['morning', 'afternoon'].first();
// 'morning'

forEachAsync

Same as forEach but works with promises. Will await async callbacks.

await [1, 2, 3].forEachAsync(async v => {
  await /* something */
});

groupBy

Returns an array of Group<K, V> extracted from the array using a callback, and an optional key comparer.

[
  { make: 'Ford', model: 'Fiesta' },
  { make: 'Ford', model: 'Focus' },
  { make: 'Vauxhall', model: 'Corsa' },
  { make: 'Vauxhall', model: 'Astra' }
].groupBy(k => k.make);
// [
//   {
//     key: 'Ford',
//     values: [
//       { make: 'Ford', model: 'Fiesta' },
//       { make: 'Ford', model: 'Focus' }
//     ]
//   },
//   {
//     key: 'Vauxhall',
//     values: [
//       { make: 'Vauxhall', model: 'Corsa' },
//       { make: 'Vauxhall', model: 'Astra' }
//     ]
//   }
// ]

innerJoin

Matches two array using a callback and returns the joined results.

const leftData = [
  { id: 1, name: 'Apples', groupId: 1 },
  { id: 2, name: 'Oranges', groupId: 1 },
  { id: 3, name: 'Cornflakes', groupId: 2 },
  { id: 4, name: 'Random', groupId: null }
];
const rightData = [
  { id: 1, name: 'Produce' },
  { id: 2, name: 'Grocery' },
  { id: 3, name: 'Confectionary' }
];

leftData.innerJoin(rightData, (l, r) => l.groupId === r.id);
// [
//   {
//     left: { id: 1, name: 'Apples', groupId: 1 },
//     right: { id: 1, name: 'Produce' }
//   },
//   {
//     left: { id: 2, name: 'Oranges', groupId: 1 },
//     right: { id: 1, name: 'Produce' }
//   },
//   {
//     left: { id: 3, name: 'Cornflakes', groupId: 2 },
//     right: { id: 2, name: 'Grocery' }
//   }
// ];

interleave

Adds new elements in between each element of an array.

['one', 'two', 'three'].interleave(() => 'and');
// ['one', 'and', 'two', 'and', 'three']

leftJoin

Matches two array using a callback and returns the joined results and unmatched results from the left array.

const leftData = [
  { id: 1, name: 'Apples', groupId: 1 },
  { id: 2, name: 'Oranges', groupId: 1 },
  { id: 3, name: 'Cornflakes', groupId: 2 },
  { id: 4, name: 'Random', groupId: null }
];
const rightData = [
  { id: 1, name: 'Produce' },
  { id: 2, name: 'Grocery' },
  { id: 3, name: 'Confectionary' }
];

leftData.leftJoin(rightData, (l, r) => l.groupId === r.id);
// [
//   {
//     left: { id: 1, name: 'Apples', groupId: 1 },
//     right: { id: 1, name: 'Produce' }
//   },
//   {
//     left: { id: 2, name: 'Oranges', groupId: 1 },
//     right: { id: 1, name: 'Produce' }
//   },
//   {
//     left: { id: 3, name: 'Cornflakes', groupId: 2 },
//     right: { id: 2, name: 'Grocery' }
//   },
//   {
//     left: { id: 4, name: 'Random', groupId: null },
//     right: null
//   }
// ];

mapAsync

Same as map but works with promises. Will await async callbacks.

await [1, 2, 3].map(async v => {
  await /* something */
  return v * 2;
});
// [2, 4, 6]

max

Returns the highest element in the array

[-10, 0, 10].max();
// 10

['a', 'b', 'c'].max();
// 'c'

[].max();
// null

min

Returns the lowest element in the array

[-10, 0, 10].min();
// -10

['a', 'b', 'c'].min();
// 'a'

[].min();
// null

none

Returns false if the array contains any elements.

[1, 2, 3].none();
// false

[].none();
// true

outerJoin

Matches two array using a callback and returns the joined results and unmatched results from both arrays.

const leftData = [
  { id: 1, name: 'Apples', groupId: 1 },
  { id: 2, name: 'Oranges', groupId: 1 },
  { id: 3, name: 'Cornflakes', groupId: 2 },
  { id: 4, name: 'Random', groupId: null }
];
const rightData = [
  { id: 1, name: 'Produce' },
  { id: 2, name: 'Grocery' },
  { id: 3, name: 'Confectionary' }
];

leftData.outerJoin(rightData, (l, r) => l.groupId === r.id);
// [
//   {
//     left: { id: 1, name: 'Apples', groupId: 1 },
//     right: { id: 1, name: 'Produce' }
//   },
//   {
//     left: { id: 2, name: 'Oranges', groupId: 1 },
//     right: { id: 1, name: 'Produce' }
//   },
//   {
//     left: { id: 3, name: 'Cornflakes', groupId: 2 },
//     right: { id: 2, name: 'Grocery' }
//   },
//   {
//     left: { id: 4, name: 'Random', groupId: null },
//     right: null
//   },
//   {
//     left: null,
//     right: { id: 3, name: 'Confectionary' }
//   }
// ];

sortBy

Returns a new array, sorted by the result of a callback function.

[
  { name: 'Brian' },
  { name: 'Albert' },
  { name: 'Charlie' }
].sortBy(v => v.name);
// [
//   { name: 'Albert' },
//   { name: 'Brian' },
//   { name: 'Charlie' }
// ]

sum

Returns the total of all the elements in the array, optionally mapping them first with a callback

[1, 10, 100].sum();
// 111

[1, 2, 3, 4].sum(v => v % 2);
// 2

toRecord

Returns a Record<K, V> extracted from the array using callbacks.

Similar in functionality to groupBy, but returns a Record, and the last value with a matching key wins

[
  { name: 'Chloe', age: 19 },
  { name: 'Daniel', age: 16 },
  { name: 'Polly', age: 12 },
  { name: 'Lottie', age: 10 },
  { name: 'Theodore', age: 8 }
].toRecord(
  k => k.name,
  v => v.age
);
// {
//   Chloe: 19,
//   Daniel: 16,
//   Polly: 12,
//   Lottie: 10,
//   Theodore: 8
// }

union

Returns only the values present in both arrays, using a comparer function if supplied, or === if not.

[1, 2, 3].union([2, 3, 4]);
// [2, 3]

[
  { day: 1, month: 1, year: 1979 },
  { day: 2, month: 1, year: 1979 }
].union(
  [
    { day: 2, month: 1, year: 1979 },
    { day: 3, month: 1, year: 1979 }
  ],
  (a, b) => a.day === b.day && a.month === b.month && a.year === b.year
);
// [
//   { day: 2, month: 1, year: 1979 }
// ]

Contributing

Contributions welcome!