The read-only didTimeout property on the IdleDeadline interface is a Boolean value which indicates whether or not the idle callback is being invoked because the timeout interval specified when Window.requestIdleCallback() was called has expired.

If didTimeout is true, the IdleDeadline object's timeRemaining() method will return approximately 0.

Idle callbacks support the concept of a timeout in order to ensure that whatever task they're meant to perform actually happens, even if the user agent never has enough idle time available. Your callback will typically check the value of didTimeout if it needs to perform an action even if the browser is too busy to grant you the time; you should react by performing the needed task or, ideally, a minimal amount of work that can be done to keep things moving along, then schedule a new callback to try again to get the rest of the work done.


var timedOut = IdleDeadline.didTimeout;


A Boolean which is true if the callback is running due to the callback's timeout period elapsing or false if the callback is running because the user agent is idle and is offering time to the callback.


See our complete example in the article Cooperative Scheduling of Background Tasks API.


Specification Status Comment
Cooperative Scheduling of Background Tasks Proposed Recommendation  

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 47 No support 53 (53)[1] No support 34 No support
Feature Android Chrome Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support 53 55 53.0 (53)[1] ? No support 37 No support

[1] Idle callback support was added in Firefox 53, but was disabled by default. To enable it, set the preference dom.requestIdleCallback.enabled to true. Idle callbacks are enabled by default starting in Firefox 55.

See also

Document Tags and Contributors

 Contributors to this page: Sheppy
 Last updated by: Sheppy,