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    void

    Summary

    The void operator evaluates the given expression and then returns undefined.

    Operator
    Implemented in: JavaScript 1.1
    ECMA Version: ECMA-262

    Syntax

    void expression

    Uses

    This operator allows inserting expressions that produce side effects into places where an expression that evaluates to undefined is desired.

    The void operator is often used merely to obtain the undefined primitive value, usually using "void(0)" (which is equivalent to "void 0"). In these cases, the global variable undefined can be used instead (assuming it has not been assigned to a non-default value).

    When wrapping an entire script in an immediately-invoked function expression, void can be used to force the function keyword to be treated as an expression instead of a declaration.

    JavaScript URIs

    When a browser follows a javascript: URI, it evaluates the code in the URI and then replaces the contents of the page with the returned value, unless the returned value is undefined. The void operator can be used to return undefined. For example:

    <a href="javascript:void(0);">Click here to do nothing</a>
    <a href="javascript:void(document.body.style.backgroundColor='green');">Click here for green background</a>
    

    Note, however, that the javascript: pseudo protocol is discouraged over other alternatives, such as unobtrusive event handlers.

    Document Tags and Contributors

    Contributors to this page: Sevenspade
    Last updated by: Sevenspade,