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; however, callbacks which have a
timeout specified may be called out-of-order if necessary in order to run them before the timeout elapses.
You can call
requestIdleCallback() within an idle callback function to schedule another callback to take place no sooner than the next pass through the event loop.
timeoutoption is strongly recommended for required work, as otherwise it's possible multiple seconds will elapse before the callback is fired.
var handle = window.requestIdleCallback(callback[, options])
An ID which can be used to cancel the callback by passing it into the
- A reference to a function that should be called in the near future, when the event loop is idle. The callback function is passed a
IdleDeadlineobject describing the amount of time available and whether or not the callback has been run because the timeout period expired.
- Contains optional configuration parameters. Currently only one property is defined:
timeoutis specified and has a positive value, and the callback has not already been called by the time timeout milliseconds have passed, the callback will be called during the next idle period, even if doing so risks causing a negative performance impact.
|Cooperative Scheduling of Background Tasks||Proposed Recommendation||Initial definition.|
|Feature||Android webview||Chrome for Android||Edge mobile||Firefox for Android||Opera Android||iOS Safari||Samsung Internet|
1. From version 53: this feature is behind the
dom.requestIdleCallback.enabled preference (needs to be set to
true). To change preferences in Firefox, visit about:config.