This is an experimental technologyCheck the Browser compatibility table carefully before using this in production.
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; 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.
A timeout
option is strongly recommended for required work, as otherwise it's possible multiple seconds will elapse before the callback is fired.
Syntax
var handle = window.requestIdleCallback(callback[, options])
Return value
An ID which can be used to cancel the callback by passing it into the window.cancelIdleCallback()
method.
Parameters
callback
- A reference to a function that should be called in the near future, when the event loop is idle. The callback function is passed an
IdleDeadline
object describing the amount of time available and whether or not the callback has been run because the timeout period expired. options
Optional- Contains optional configuration parameters. Currently only one property is defined:
timeout
- If
timeout
is 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.
- If
Example
See our complete example in the article Cooperative Scheduling of Background Tasks API.
Specifications
Specification | Status | Comment |
Cooperative Scheduling of Background Tasks | Proposed Recommendation | Initial definition. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Chrome
Full support 47 |
Edge
Full support 79 |
Firefox Full support 55 Full support 55 Notes' Enabled by default. No support 53 — 55 Notes' Implemented but disabled by default. |
IE
No support No |
Opera
Full support 34 |
Safari
No support No |
WebView Android
Full support 47 |
Chrome Android
Full support 47 |
Firefox Android Full support 55 Full support 55 Notes' Enabled by default. No support 53 — 55 Notes' Implemented but disabled by default. |
Opera Android
Full support 34 |
Safari iOS
No support No |
Samsung Internet Android
Full support 5.0 |
Legend
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.'
- Experimental. Expect behavior to change in the future.
- See implementation notes.'
- See implementation notes.
See also
window.cancelIdleCallback()
IdleDeadline
window.setTimeout()
window.setInterval()
window.requestAnimationFrame
window.requestIdleCallback() by Mozilla Contributors is licensed under CC-BY-SA 2.5.