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Window: setImmediate() method

files/en-us/web/api/window/setimmediate/index.md

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{{APIRef("HTML DOM")}} {{deprecated_header}}{{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

js-nolint
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