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    Window.setImmediate()

    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.

    Note: This method is not expected to become standard, and is only implemented by recent builds of Internet Explorer and Node.js 0.10+. It meets resistance both from Gecko (Firefox) and Webkit (Google/Apple).

    Syntax

    var immediateID = setImmediate(func, [param1, param2, ...]);
    var immediateID = setImmediate(func);
    
    • where immediateID is the ID of the immediate which can be used later with window.clearImmediate.
    • func is the function you wish to call.

    All parameters will be passed directly to your function.

    Notes

    The window.clearImmediate method can be used to clear the immediate actions, just like window.clearTimeout for window.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:

    • window.postMessage can be used to trigger an immediate but yielding callback. Do note that Internet Explorer 8 includes a synchronous version of postMessage, 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 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.

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support Not supported Not supported 10 Not supported Not supported
    Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support Not supported Not supported Not supported Not supported Not supported

    See also

    window.clearImmediate

    Specification: Efficient Script Yielding

    Microsoft setImmediate API Demo

    Document Tags and Contributors

    Last updated by: kscarfone,