Maybe Later

maybe-later defers the execution of functions at a later time. Deferring a function returns a method that cancels the function execution.

maybe-later is more resource friendly and faster than simply stacking requestAnimationFrame or setTimeout calls: every deferred function belonging to the same call stack with the same timeout gets executed inside the same call, at the same time.

When using maybe-later for animations everything will be synced properly.

Basic usage

const defer = require('maybe-later')
const cancel1 = defer(() => {
  console.log('hello immediate')
})
 
const cancel2 = defer(() => {
  console.log('hello timeout')
}, 100)
 
// if you change your mind
cancel1()
cancel2()

defer() is an alias for defer.immediate() when called with no second argument, and defer.timeout() when the second argument is a number (timeout in milliseconds).

Method: immediate

Defers the execution of a function in the next iteration loop, as soon as possible. Uses setImmediate where available, falls back to setTimeout(0).

const defer = require('maybe-later')
defer.immediate(() => {
  console.log('hello world')
})

Method: frame

Like defer.immediate, however defer.frame defers the execution of a function on the next animation frame. If requestAnimationFrame is not available, defer.frame falls back to setTimeout with a 1000 / 60 delay.

const defer = require('maybe-later')
defer.frame(() => {
  console.log('hello world')
})

Method: timeout

Defers the execution of a function after a specified number of milliseconds.

const defer = require('maybe-later')
defer.timeout(() => {
  console.log('hello world')
}, 1000)

Method: once

Automatically cancels the previous call of the same name.

const fs = require('fs')
const defer = require('defer')
 
fs.watch(FILE_PATH, () => {
  defer.once('file-change', () => console.log('done something expensive'), 1000)
})

Method: wait

Returns a promise that resolves (with the current time as a value) after the specified amount of time (or on setImmediate when no time argument is passed).

const defer = require('defer')
(async () => {
  const now = await defer.wait(1000)
  console.log('waited 1 second', now)
})()

Time argument

A time argument is passed to each function of the stack, which is the date at which the stack has begun processing. This ensures each function of the same stack receives the same time argument.