Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
This method is used to break up long running operations and run a callback function immediately after the browser has completed other operations such as events and display updates.
Syntax
var immediateID = setImmediate(func, [param1, param2, ...]); var immediateID = setImmediate(func);
- where
immediateID
is the ID of the immediate which can be used later withwindow.clearImmediate
. func
is the function you wish to call.
All parameters will be passed directly to your function.
Notes
The clearImmediate
method can be used to clear the immediate actions, just like clearTimeout
for setTimeout
.
This method can be used instead of the setTimeout(fn, 0)
method to execute heavy operations.
The feature can be emulated in a few different ways:
postMessage
can be used to trigger an immediate but yielding callback. Do note that Internet Explorer 8 includes a synchronous version ofpostMessage
, which means it cannot be used as a fallback.MessageChannel
can be used reliably inside of Web Workers whereas the semantics of postMessage mean it cannot be used there.setTimeout(fn, 0)
can potentially be used, however as it is clamped to 4ms for timers nested more than 5 levels deep per the HTML spec, it does not make for a suitable polyfill for the natural immediacy ofsetImmediate
.
All of these techniques are incorporated into a robust setImmediate polyfill.
Specifications
Specification | Status | Comment |
---|---|---|
Efficient Script Yielding The definition of ' setImmediate ' in that specification. |
Editor's Draft | Initial definition. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
setImmediate | Chrome No support No | Edge No support 12 — 79 | Firefox No support No | IE Full support 10 | Opera No support No | Safari No support No | WebView Android No support No | Chrome Android No support No | Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android No support No |
Legend
- Full support
- Full support
- No support
- No support
- Non-standard. Expect poor cross-browser support.
- Non-standard. Expect poor cross-browser support.