Window: setImmediate() method

{{APIRef("HTML DOM")}} {{non-standard_header}}

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

setImmediate(func)
setImmediate(func, param1)
setImmediate(func, param1, param2)
setImmediate(func, param1, param2, /* …, */ paramN)

Parameters

• func

  • : The function you wish to call.

• param1, …, paramN

  • : All parameters will be passed directly to your function.

Return value

The ID of the immediate which can be used later with {{DOMxRef("window.clearImmediate")}}.

Notes

The {{DOMxRef("Window.clearImmediate", "clearImmediate()")}} method can be used to clear the immediate actions, just like {{DOMxRef("Window.clearTimeout", "clearTimeout()")}} for {{DOMxRef("Window.setTimeout", "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:

• {{DOMxRef("Window.postMessage", "postMessage()")}} can be used to trigger an immediate but yielding callback.
• {{DOMxRef("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 of setImmediate.

All of these techniques are incorporated into a robust setImmediate polyfill.

Specifications

Not part of any current specifications. The Efficient Script Yielding specification is no longer being worked on.

Browser compatibility

{{Compat}}

See also

• Polyfill of setImmediate in core-js
• Microsoft setImmediate API Demo
• {{DOMxRef("Window.clearImmediate()")}}
• {{DOMxRef("Window.requestIdleCallback()")}}