yahtnif/randelay

Random + delay + ms

Install

$ npm install randelay

Usage

const delay = require('randelay')

;(async () => {
  bar()

  await delay(100)

  // Executed 100 milliseconds later
  baz()

  // Or
  await delay('1s')

  await delay(100, 500)

  await delay(100, '1s')

  await delay('5s', '1m')

  await delay(['5s', '1m'])
})()

API

delay(time, [endTime], [options])

Create a promise which resolves after the specified time or the random time range in (time, endTime).

delay.reject(time, [endTime], [options])

Create a promise which rejects after the specified time or the random time range in (time, endTime).

time

Type: number | string | Array

Time to delay the promise. See ms.

endTime

Type: number | string

Random time range in (time, endTime) to delay the promise. See ms.

options

Type: Object

value

Type: any

Optional value to resolve or reject in the returned promise.

signal

Type: AbortSignal

The returned promise will be rejected with an AbortError if the signal is aborted. AbortSignal is available in all modern browsers and there is a ponyfill for Node.js.

delayPromise.clear()

Clears the delay and settles the promise.

delay.createWithTimers({clearTimeout, setTimeout})

Creates a new delay instance using the provided functions for clearing and setting timeouts. Useful if you're about to stub timers globally, but you still want to use delay to manage your tests.

Advanced usage

Passing a value:

const delay = require('randelay')

;(async () => {
  const result = await delay(100, { value: '🦄' })

  // Executed after 100 milliseconds
  console.log(result)
  //=> '🦄'
})()

Using delay.reject(), which optionally accepts a value and rejects it ms later:

const delay = require('randelay')

;(async () => {
  try {
    await delay.reject(100, { value: new Error('🦄') })

    console.log('This is never executed')
  } catch (error) {
    // 100 milliseconds later
    console.log(error)
    //=> [Error: 🦄]
  }
})()

You can settle the delay early by calling .clear():

const delay = require('randelay')

;(async () => {
  const delayedPromise = delay(1000, { value: 'Done' })

  setTimeout(() => {
    delayedPromise.clear()
  }, 500)

  // 500 milliseconds later
  console.log(await delayedPromise)
  //=> 'Done'
})()

You can abort the delay with an AbortSignal:

const delay = require('randelay')

;(async () => {
  const abortController = new AbortController()

  setTimeout(() => {
    abortController.abort()
  }, 500)

  try {
    await delay(1000, { signal: abortController.signal })
  } catch (error) {
    // 500 milliseconds later
    console.log(error.name)
    //=> 'AbortError'
  }
})()

Create a new instance that is unaffected by libraries such as lolex:

const delay = require('randelay')

const customDelay = delay.createWithTimers({ clearTimeout, setTimeout })

;(async () => {
  const result = await customDelay(100, { value: '🦄' })

  // Executed after 100 milliseconds
  console.log(result)
  //=> '🦄'
})()

License

Anti 996

yahtnif / randelay