The IdleDeadline interface is used as the data type of the input parameter to idle callbacks established by calling Window.requestIdleCallback(). It offers a method, timeRemaining(), which lets you determine how much longer the user agent estimates it will remain idle and a property, didTimeout, which lets you determine if your callback is executing because its timeout duration expired.
To learn more about how request callbacks work, see Collaborative Scheduling of Background Tasks.
Properties
IdleDeadline.didTimeoutRead only- A Boolean whose value is
trueif the callback is being executed because the timeout specified when the idle callback was installed has expired.
Methods
IdleDeadline.timeRemaining()- Returns a
DOMHighResTimeStamp, which is a floating-point value providing an estimate of the number of milliseconds remaining in the current idle period. If the idle period is over, the value is 0. Your callback can call this repeatedly to see if there's enough time left to do more work before returning.
Example
See our complete example in the article Cooperative Scheduling of Background Tasks API.
Specifications
| Specification | Status | Comment |
|---|---|---|
| Cooperative Scheduling of Background Tasks | Working Draft |
Browser compatibility
| 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.