requestIdleCallback

The window.requestIdleCallback() method queues a function to be called during a browser's idle periods. This enables developers to perform background and low priority work on the main event loop, without impacting latency-critical events such as animation and input response. Functions are generally called in first-in-first-out order unless the function's timeout is reached before the browser calls it.

Syntax

var handle = window.requestIdleCallback(callback[, options])

Returns

An unsigned long integer that can be used to cancel the callback using the Window.cancelIdleCallback() method.

Parameters

callback

A reference to a function that should be called in the near future. The callback function takes a deadline argument with the following properties:

• timeRemaining: A reference to a method that returns a DOMHighResTimeStamp.
• didTimeout: A boolean that returns false if the callback was invoked by the user agent during idle, and true otherwise (e.g. if a timeout option was given and expired before there was sufficient idle time).

options Optional

Contains optional configuration parameters. It has the following property:

• timeout: A deadline by which the browser must call the given callback function. This value is given in milliseconds.

Specifications

Browser compatibility