Socket
Socket
Sign inDemoInstall

async-array-methods

Package Overview
Dependencies
6
Maintainers
1
Versions
6
Alerts
File Explorer

Advanced tools

Install Socket

Detect and block malicious and high-risk dependencies

Install

async-array-methods

Async methods to operate on collections


Version published
Maintainers
1
Weekly downloads
34
increased by100%

Weekly downloads

Readme

Source

async-array-methods

version status coverage dependencies devDependencies

Async methods to manipulate arrays.

Usage

var methods = require('async-array-methods')
var AsyncArray = methods.Array
var filter = methods.filter
var map = methods.map
var forEach = methods.forEach
var reduce = methods.reduce

All methods return a promise.

Methods

Callbacks can be made asynchronous by returning a promise, or accepting a function argument, which will be called when the callback finishes.

Otherwise, the callback is treated as synchronous.

filter

Signature: filter(arr, fn, context)

filter(
  [1, 2, 3, 4],
  function (v, i, a, next) {
    process.nextTick(function () {
      next(null, v % 2)
    })
  }
)
.then(function (res) {
  // [1, 3]
  console.log(res)
})

map

Signature: map(arr, fn, context)

fn is called with each element in parallel.

map(
  [1, 2, 3, 4],
  function (v) {
    return new Promise(function (rs) {
      process.nextTick(function () {
        rs(v << 2)
      })
    })
  },
  { num: 2 }
)
// [4, 8, 12, 16]
.then(console.log.bind(console))

series

This method works like map, except that fn is called with each element in sequence rather than in parallel.

Signature: map(arr, fn, context)

var n = 1
series(
  [1, 2, 3, 4],
  function (v, i, arr, next) {
    var delay = rand()
    console.log('i:', i, 'delay:', delay)
    setTimeout(function() {
      next(null, v << n++)
    }, delay)
  }
)
// i: 0 delay: 10
// i: 1 delay: 50
// i: 2 delay: 0
// i: 3 delay: 80
// [2, 8, 24, 64]
.then(log)

function rand() {
  return Math.floor(Math.random() * 10) * 10
}

forEach

fn is called with elements in sequence.

Signature: forEach(arr, fn, context)

var count = 0

forEach(
  [1, 2, 3, 4],
  function (v, i, _, next) {
    process.nextTick(function () {
      console.log(count++, i)
      next(null, v << 2)
    })
  }
)
.then(function (arr) {
  // [1, 2, 3, 4]
  console.log(arr)
})

reduce

Signature: reduce(arr, fn, initial)

reduce(
  [1, 2, 3, 4],
  function (a, b, i, arr, next) {
    process.nextTick(function () {
      next(null, a + b)
    })
  }
)
// 10
.then(console.log.bind(console))

AsyncArray

Signature: AsyncArray(arr)

Methods:

  • map
  • series
  • filter
  • forEach
  • reduce
var origin = AsyncArray([1, 2, 3, 4, 5, 6])
var odd = origin.filter(isOdd)
var even = origin.filter(isEven)

return odd.then(function (res) {
  // [1, 3, 5]
  console.log(res)
  return even
})
.then(function (res) {
  // [2, 4, 6]
  console.log(res)
})
.then(function () {
  return even.reduce(flagMap, {})
})
.then(function (res) {
  // { 2: true, 4: true, 6: true }
  console.log(res)
})
.then(function () {
  // chain
  return origin.filter(isOdd).reduce(flagMap, {})
})
.then(function (res) {
  // { 1: true, 3: true, 5: true }
  console.log(res)
})

function isOdd(n, i, arr, next) {
  process.nextTick(function () {
    next(null, n % 2)
  })
}

function isEven(n, i, arr, next) {
  return new Promise(function (resolve) {
    process.nextTick(function () {
      resolve((n + 1) % 2)
    })
  })
}

function flagMap(o, v) {
  o[v] = true
  return o
}

Keywords

FAQs

Last updated on 10 Dec 2015

Did you know?

Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.

Install

Related posts

SocketSocket SOC 2 Logo

Product

  • Package Alerts
  • Integrations
  • Docs
  • Pricing
  • FAQ
  • Roadmap

Stay in touch

Get open source security insights delivered straight into your inbox.


  • Terms
  • Privacy
  • Security

Made with ⚡️ by Socket Inc