Package Exports

iterable-operator
iterable-operator/lib/es2018/style/chaining
iterable-operator/lib/es2018/style/chaining/iterable-operator

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (iterable-operator) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

iterable-operator

Utilities for JavaScript Iterable and AsyncIterable.

Install

npm install --save iterable-operator
# or
yarn add iterable-operator

Usage

import { map, toArray } from 'iterable-operator'

const iter = [1, 2, 3]
const doubleIter = map(iter, x => x * 2)
const result = toArray(doubleIter)

You may need a pipe function.

API

isIterable

function isIterable<T>(val: unknown): val is Iterable<T>
function isntIterable<T>(val: T): val is Exclude<T, Iterable<unknown>>

isAsyncIterable

function isAsyncIterable<T>(val: unknown): val is AsyncIterable<T>
function isntAsyncIterable<T>(
  val: T
): val is Exclude<T, AsyncIterable<unknown>>

chunk, chunkAsync

function chunk<T>(
  iterable: Iterable<T>
, size: number // size > 0
): IterableIterator<T[]>
function chunkAsync<T>(
  iterable: AsyncIterable<T>
, size: number // size > 0
): AsyncIterableIterator<Array<Awaited<T>>>

chunk([1, 2, 3], 2) // [[1, 2], [3]]
chunk([1, 2, 3], 3) // [[1, 2, 3]]
chunk([1, 2, 3], 5) // [[1, 2, 3]]
chunk([1, 2, 3], 0) // throw Error
chunk([1, 2, 3], -1) // throw Error

The memory usage of this function depends on size.

chunkBy, chunkByAsync

function chunkBy<T>(
  iterable: Iterable<T>
, predicate: (element: T, index: number) => unknown
): IterableIterator<T[]>
function chunkByAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, predicate: (element: Awaited<T>, index: number) => Awaitable<unknown>
): AsyncIterableIterator<Array<Awaited<T>>>

chunkBy([1, 2, 3], x => x === 2) // [[1, 2], [3]]
chunkBy([1, 2, 3], x => x === 3) // [[1, 2, 3]]
chunkBy([1, 2, 3], x => x === 5) // [[1, 2, 3]]

The memory usage of this function depends on iterable and predicate.

concat, concatAsync

function concat<T, U>(
  iterable: Iterable<T>
, ...otherIterables: Iterable<U>[]
): IterableIterator<T | U>
function concatAsync<T, U>(
  iterable: Iterable<T> | AsyncIterable<T>
, ...otherIterables: Array<Iterable<Awaitable<U>> | AsyncIterable<Awaitable<U>>>
): AsyncIterableIterator<Awaited<T> | Awaited<U>>

concat([1, 2, 3]) // [1, 2, 3]
concat([1, 2, 3], ['a', 'b', 'c']) // [1, 2, 3, 'a', 'b', 'c']

difference, differenceAsync

function difference<T>(left: Iterable<T>, right: Iterable<T>): IterableIterator<T>
function differenceAsync<T>(
  left: Iterable<Awaitable<T>> | AsyncIterable<Awaitable<T>>
, right: Iterable<Awaitable<T>> | AsyncIterable<Awaitable<T>>
): AsyncIterableIterator<Awaited<T>>

difference([1, 2, 3], [3, 4, 5]) // [1, 2]

The memory usage of this function depends on right.

drop, dropAsync

function drop<T>(
  iterable: Iterable<T>
, count: number // count >= 0
): IterableIterator<T>
function dropAsync<T>(
  iterable: AsyncIterable<T>
, count: number // count >= 0
): AsyncIterableIterator<Awaited<T>>

drop([1, 2, 3], 0) // [1, 2, 3]
drop([1, 2, 3], 2) // [3]
drop([1, 2, 3], 3) // []
drop([1, 2, 3], 5) // []
drop([1, 2, 3], -1) // throw Error

dropRight, dropRightAsync

function dropRight<T>(
  iterable: Iterable<T>
, count: number // count >= 0
): IterableIterator<T>
function dropRightAsync<T>(
  iterable: AsyncIterable<T>
, count: number // count >= 0
): AsyncIterableIterator<Awaited<T>>

dropRight([1, 2, 3], 0) // [1, 2, 3]
dropRight([1, 2, 3], 2) // [1]
dropRight([1, 2, 3], 3) // []
dropRight([1, 2, 3], 5) // []
dropRight([1, 2, 3], -1) // throw Error

The memory usage of this function depends on iterable.

dropUntil, dropUntilAsync

function dropUntil<T>(
  iterable: Iterable<T>
, predicate: (element: T, index: number) => unknown
): IterableIterator<T>
function dropUntilAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, predicate: (element: Awaited<T>, index: number) => Awaitable<unknown>
): AsyncIterableIterator<Awaited<T>>

dropUntil([1, 2, 3], x => x === 2) // [2, 3]

The memory usage of this function depends on iterable and predicate.

filter, filterAsync

function filter<T, U extends T = T>(
  iterable: Iterable<T>
, predicate: (element: T, index: number) => unknown
): IterableIterator<U>
function filterAsync<T, U extends Awaited<T> = Awaited<T>>(
  iterable: Iterable<T> | AsyncIterable<T>
, predicate: (element: Awaited<T>, index: number) => Awaitable<unknown>
): AsyncIterableIterator<U>

filter([1, 2, 3], x => x % 2 === 1) // [1, 3]

flatten, flattenAsync

function flatten<T>(iterable: Iterable<unknown>): IterableIterator<T>
function flattenAsync<T>(iterable: AsyncIterable<unknown>): AsyncIterableIterator<T>

flatten([]) // []
flatten('123') // ['1', '2', '3']
flatten(['one', ['two'], 0, [1, [2]]]) // ['o', 'n', 'e', 'two', 0, 1, [2]]

flattenDeep, flattenDeepAsync

function flattenDeep<T>(
  iterable: Iterable<unknown>
, depth: number = Infinity // depth >= 0
): IterableIterator<T>
function flattenDeepAsync<T>(
  iterable: AsyncIterable<unknown>
, depth: number = Infinity // depth >= 0
): AsyncIterableIterator<T>

flattenDeep([]) // []
flattenDeep('123') // ['1', '2', '3']
flattenDeep([], -1) // throw Error
flattenDeep([0, [1]], 0) // [0, [1]]
flattenDeep(['one', ['two', ['three']], 0, [1, [2, [3]]]], 2) // ['o', 'n', 'e', 't', 'w', 'o', 'three', 0, 1, 2, [3]]

flattenBy, flattenByAsync

function flattenBy<T>(
  iterable: Iterable<unknown>
, predicate: (element: unknown, level: number) => boolean
): IterableIterator<T>
function flattenByAsync<T>(
  iterable: Iterable<unknown> | AsyncIterable<unknown>
, predicate: (element: unknown, level: number) => Awaitable<unknown>
): AsyncIterableIterator<T>

flattenBy(['one', ['two'], 0, [1]], x => typeof x !== 'string') // ['one', 'two', 0, 1]
flattenBy([], () => true) // []
flattenBy('123', () => true) // ['1', '2', '3']

intersection, intersectionAsync

function intersection<T>(left: Iterable<T>, right: Iterable<T>): IterableIterator<T>
function intersectionAsync<T>(
  left: Iterable<Awaitable<T>> | AsyncIterable<T>
, right: Iterable<Awaitable<T>> | AsyncIterable<T>
): AsyncIterableIterator<Awaited<T>>

The memory usage of this function depends on right.

intersection([1, 2], [2, 3]) // [2]

map, mapAsync

function map<T, U>(
  iterable: Iterable<T>
, fn: (element: T, index: number) => U
): IterableIterator<U>
function mapAsync<T, U>(
  iterable: Iterable<T> | AsyncIterable<T>
, fn: (element: Awaited<T>, index: number) => Awaitable<U>
): AsyncIterableIterator<Awaited<U>>

map([1, 2, 3], x => x * 2) // [2, 4, 6]

flatMap, flatMapAsync

function flatMap<T, U>(
  iterable: Iterable<T>
, fn: (element: T, index: number) => Iterable<U>
): IterableIterator<U>
function flatMapAsync<T, U>(
  iterable: Iterable<T> | AsyncIterable<T>
, fn: (element: Awaited<T>, index: number) => Awaitable<Iterable<U> | AsyncIterable<U>>
): AsyncIterableIterator<Awaited<U>>

map([1, 2, 3], x => [x, x * 2]) // [1, 2, 2, 4, 3, 6]

repeat, repeatAsync

function repeat<T>(
  iterable: Iterable<T>
, times: number // times >= 0
): IterableIterator<T>
function repeatAsync<T>(
  iterable: AsyncIterable<T>
, times: number // times >= 0
): AsyncIterableIterator<Awaited<T>>

repeat([1, 2, 3], 2) // [1, 2, 3, 1, 2, 3]
repeat([1, 2, 3], 0) // []
repeat([1, 2, 3], -1) // throw Error

The memory usage of this function depends on iterable.

slice, sliceAsync

function slice<T>(
  iterable: Iterable<T>
, start: number // start >= 0
, end: number = Infinity // end >= start
): IterableIterator<T>
function sliceAsync<T>(
  iterable: AsyncIterable<T>
, start: number // start >= 0
, end: number = Infinity // end >= start
): AsyncIterableIterator<Awaited<T>>

slice([1, 2, 3], -1, 1) // throw Error
slice([1, 2, 3], 3, 5) // []
slice([1, 2, 3], 1, 2) // [2]
slice([1, 2, 3], 1, 1) // []
slice([1, 2, 3], 2, 1) // throw Error

join, joinAsync

function join<T, U = T>(iterable: Iterable<T>, separator: U): IterableIterator<T | U>
function joinAsync<T, U = T>(
  iterable: AsyncIterable<T>
, separator: U
): AsyncIterableIterator<Awaited<T> | U>

join([1, 2, 3], '+') // [1, '+', 2, '+', 3]

split, splitAsync

function split<T>(iterable: Iterable<T>, separator: T): IterableIterator<T[]>
function splitAsync<T>(
  iterable: AsyncIterable<T>
, separator: T
): AsyncIterableIterator<Array<Awaited<T>>>

split([1, 2, 3, 4, 5], 3) // [[1, 2], [4, 5]]
split([1, 2, 3, 4, 5], 1) // [[], [2, 3, 4, 5]]
split([1, 2, 3, 4, 5], 5) // [[1, 2, 3, 4], []]
split([1, 2, 3, 4, 5], 0) // [[1, 2, 3, 4, 5]]

The memory usage of this function depends on iterable and separator.

splitBy, splitByAsync

function splitBy<T>(
  iterable: Iterable<T>
, predicate: (element: T, index: number) => unknown
): IterableIterator<T[]>
function splitByAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, predicate: (element: Awaited<T>, index: number) => Awaitable<unknown>
): AsyncIterableIterator<Array<Awaited<T>>>

splitBy([1, 2, 3, 4, 5], x => x === 3) // [[1, 2], [4, 5]]
splitBy([1, 2, 3, 4, 5], x => x === 1) // [[], [2, 3, 4, 5]]
splitBy([1, 2, 3, 4, 5], x => x === 5) // [[1, 2, 3, 4], []]
splitBy([1, 2, 3, 4, 5], x => x === 0) // [[1, 2, 3, 4, 5]]

The memory usage of this function depends on iterable and predicate.

take, takeAsync

function take<T>(iterable: Iterable<T>, count: number): IterableIterator<T>
function takeAsync<T>(
  iterable: AsyncIterable<T>
, count: number
): AsyncIterableIterator<Awaited<T>>

take([1, 2, 3], 5) // [1, 2, 3]
take([1, 2, 3], 2) // [1, 2]
take([1, 2, 3], 0) // []
take([1, 2, 3], -1) // throw Error

takeRight, takeRightAsync

function takeRight<T>(iterable: Iterable<T>, count: number): IterableIterator<T>
function takeRightAsync<T>(
  iterable: AsyncIterable<T>
, count: number
): AsyncIterableIterator<Awaited<T>>

takeRight([1, 2, 3], 2) // [2, 3]
takeRight([1, 2, 3], 5) // [1, 2, 3]
takeRight([1, 2, 3], 0) // []
takeRight([1, 2, 3], -1) // throw Error

The memory usage of this function depends on count.

takeUntil, takeUntilAsync

function takeUntil<T>(
  iterable: Iterable<T>
, predicate: (element: T, index: number) => unknown
): IterableIterator<T>
function takeUntilAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, predicate: (element: Awaited<T>, index: number) => Awaitable<unknown>
): AsyncIterableIterator<Awaited<T>>

takeUntil([1, 2, 3], x => x === 2) // [1]

tap, tapAsync

function tap<T>(
  iterable: Iterable<T>
, fn: (element: T, index: number) => unknown
): IterableIterator<T>
function tapAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, fn: (element: Awaited<T>, index: number) => Awaitable<unknown>
): AsyncIterableIterator<Awaited<T>>

tap([1, 2, 3], x => console.log(x)) // [1, 2, 3]

toAsyncIterable

function toAsyncIterable<T>(
  iterable: Iterable<Awaitable<T>>
): AsyncIterableIterator<Awaited<T>>

toAsyncIterable([1, 2, 3]) // AsyncIterable [1, 2, 3]

transform, transformAsync

function transform<T, U>(
  iterable: Iterable<T>
, transformer: (iterable: Iterable<T>) => Iterable<U>
): IterableIterator<U>
function transformAsync<T, U>(
  iterable: Iterable<T>
, transformer: (iterable: Iterable<T>) => AsyncIterable<U>
): AsyncIterableIterator<Awaited<U>>
function transformAsync<T, U>(
  iterable: AsyncIterable<T>
, transformer: (iterable: AsyncIterable<T>) => AsyncIterable<U>
): AsyncIterableIterator<Awaited<U>>

transform([1, 2, 3], function* double(iter) {
  for (const element of iter) {
    yield element * 2
  }
}) // [2, 4, 6]

uniq, uniqAsync

function uniq<T>(iterable: Iterable<T>): IterableIterator<T>
function uniqAsync<T>(iterable: AsyncIterable<T>): AsyncIterableIterator<Awaited<T>>

uniq([1, 1, 2, 2, 3, 3]) // [1, 2, 3]

The memory usage of this function depends on iterable.

uniqBy, uniqByAsync

function uniqBy<T, U>(
  iterable: Iterable<T>
, fn: (element: T, index: number) => U
): IterableIterator<T>
function uniqByAsync<T, U>(
  iterable: Iterable<T> | AsyncIterable<T>
, fn: (element: Awaited<T>, index: number) => Awaitable<U>
): AsyncIterableIterator<Awaited<T>>

uniqBy([1, 2, 3], x => x % 2) // [1, 2]

The memory usage of this function depends on fn.

zip, zipAsync

function zip<T, U extends Array<Iterable<unknown>>>(
  iterable: Iterable<T>
, ...otherIterables: U
): IterableIterator<[T, ...ExtractTypeTupleFromIterableTuple<U>]>
function zipAsync<
  T
, U extends Array<Iterable<Awaitable<unknown>> | AsyncIterable<Awaitable<unknown>>>
>(
  iterable: Iterable<Awaitable<T>> | AsyncIterable<Awaitable<T>>
, ...otherIterables: U
): AsyncIterableIterator<
  [Awaited<T>, ...ExtractTypeTupleFromAsyncLikeIterableTuple<U>]
>

zip([1, 2, 3], ['a', 'b', 'c']) // [[1, 'a'], [2, 'b'], [3, 'c']]
zip([1, 2, 3], ['a', 'b']) // [[1, 'a'], [2, 'b']
zip([1, 2, 3], ['a', 'b'], ['i', 'ii', 'iii']) // [[1, 'a', 'i'], [2, 'b', 'ii']]

consume, consumerAsync

function consume<T, U>(iterable: Iterable<T>, consumer: (iterable: Iterable<T>) => U): U
function consumeAsync<T, U>(
  iterable: Iterable<T>
, consumer: (iterable: Iterable<T>) => Awaitable<U>
): Promise<Awaited<U>>
function consumeAsync<T, U>(
  iterable: AsyncIterable<T>
, consumer: (iterable: AsyncIterable<T>) => Awaitable<U>
): Promise<Awaited<U>>

consume([1, 2, 3], xs => new Set(xs)) // Set [1, 2, 3]

each, eachAsync

function each<T>(
  iterable: Iterable<T>
, fn: (element: T, index: number) => unknown
): void
function eachAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, fn: (element: Awaited<T>, index: number) => Awaitable<unknown>
): Promise<void>

each([1, 2, 3], x => console.log(x)) // void

every, everyAsync

function every<T>(
  iterable: Iterable<T>
, predicate: (element: T, index: number) => unknown
): boolean
function everyAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, predicate: (element: Awaited<T>, index: number) => Awaitable<unknown>
): Promise<boolean>

every([1, 2, 3], x => x < 5) // true
every([1, 2, 3], x => x <= 2) // false

find, findAsync

function find<T>(
  iterable: Iterable<T>
, predicate: (element: T, index: number) => unknown
): T | undefined
function findAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, predicate: (element: Awaited<T>, index: number) => Awaitable<unknown>
): Promise<Awaited<T> | undefined>

find([1, 2, 3], x => x === 2) // 2
find([1, 2, 3], x => x === 4) // undefined

findAllIndexes

function findAllIndexes<T>(
  iterable: Iterable<T>
, predicate: (value: T, index: number) => unknown
): IterableIterator<number>

findAllIndexes([1, 2, 3], x => x % 2 === 1) // [0, 2]

first, firstAsync

function first<T>(iterable: Iterable<T>): T | undefined
function firstAsync<T>(iterable: AsyncIterable<T>): Promise<Awaited<T> | undefined>

first([1, 2, 3]) // 1
first([]) // undefined

includes, includesAsync

function includes<T>(iterable: Iterable<T>, value: T): boolean
function includesAsync<T>(
  iterable: AsyncIterable<T>
, value: Awaited<T>
): Promise<boolean>

includes([1, 2, 3], 2) // true
includes([1, 2, 3], 4) // false

last, lastAsync

function last<T>(iterable: Iterable<T>): T | undefined
function lastAsync<T>(iterable: AsyncIterable<T>): Promise<Awaited<T> | undefined>

last([1, 2, 3]) // 3
last([]) // undefined

reduce, reduceAsync

function reduce<T>(
  iterable: Iterable<T>
, fn: (accumulator: T, currentValue: T, index: number) => T
): T
function reduce<T, U>(
  iterable: Iterable<T>
, fn: (accumulator: U, currentValue: T, index: number) => U
, initialValue: U
): U
function reduceAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, fn: (
    accumulator: Awaited<T>
  , currentValue: Awaited<T>
  , index: number
  ) => Awaitable<Awaited<T>>
): Promise<Awaited<T>>
function reduceAsync<T, U>(
  iterable: Iterable<T> | AsyncIterable<T>
, fn: (accumulator: Awaited<U>, currentValue: Awaited<T>, index: number) => Awaitable<U>
, initialValue: U
): Promise<Awaited<U>>

reduce([], (acc, cur) => acc + cur) // throw Error
reduce([1], (acc, cur) => acc + cur) // 1
reduce([1, 2, 3], (acc, cur) => acc + cur) // 6

reduce([1, 2, 3], (acc, cur, index) => {
  acc.push([cur, index])
  return acc
}) // [[1, 0], [2, 1], [3, 2]]

some, someAsync

function some<T>(
  iterable: Iterable<T>
, predicate: (element: T, index: number) => unknown
): boolean
function someAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
, predicate: (element: Awaited<T>, index: number) => Awaitable<unknown>
): Promise<boolean>

some([1, 2, 3], x => x === 2) // true
some([1, 2, 3], x => x === 4) // false

toArray, toArrayAsync

function toArray<T>(iterable: Iterable<T>): T[]
function toArrayAsync<T>(
  iterable: AsyncIterable<T>
): Promise<Array<Awaited<T>>>

toArray([1, 2, 3]) // Array [1, 2, 3]

toSet, toSetAsync

function toSet<T>(iterable: Iterable<T>): Set<T>
function toSetAsync<T>(
  iterable: Iterable<T> | AsyncIterable<T>
): Promise<Set<Awaited<T>>>

toSet([1, 1, 2, 2, 3, 3]) // Set [1, 2, 3]

count, countAsync

function count(iterable: Iterable<unknown>): number
function countAsync(iterable: AsyncIterable<unknown>): Promise<number>

count([1, 2, 3]) // 3

groupBy, groupByAsync

function groupBy<T, U>(
  iterable: Iterable<T>
, fn: (element: T, index: number) => U
): Map<U, T[]>
function groupByAsync<T, U>(
  iterable: Iterable<T> | AsyncIterable<T>
, fn: (element: Awaited<T>, index: number) => Awaitable<U>
): Promise<Map<Awaited<U>, Array<Awaited<T>>>>

groupBy([1, 2, 3], x => x % 2) // { 1: [1, 3], 0: [2] }

prefetch, prefetchAsync

function prefetch<T>(iterable: Iterable<T>, size: number): AsyncIterableIterator<T>
function prefetchAsync<T>(
  iterable: AsyncIterable<T>
, size: number
): AsyncIterableIterator<T>

top, topAsync

function top<T>(
  iterable: Iterable<T>
, num: number
, compare: (a: T, b: T) => number
): T[]
function topAsync<T>(
  iterable: AsyncIterable<T>
, num: number
, compare: (a: Awaited<T>, b: Awaited<T>) => number
): Promise<Array<Awaited<T>>>

top([1, 2, 3], 2, (a, b) => b - a) // [3, 2]

avg, avgAsync

function avg(iterable: Iterable<number>): number
function avgAsync(iterable: AsyncIterable<number>): Promise<number>

avg([1, 2, 3]) // 2