Immediately invoked function expression: Difference between revisions

Revision as of 10:41, 29 March 2017

Revision as of 16:23, 2 May 2017

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==Usage==

Immediately-invoked function expressions may be written in a number of different ways.<ref name=Enlighten>{{cite book|last=Lindley|first=Cody|title=JavaScript Enlightenment|year=2013|publisher=O'Reilly|isbn=9781449342883|pages=61}}</ref> A [[Coding conventions|common convention]] is to enclose the function expression (and optionally its invocation operator—[[Douglas Crockford]]'s styleoperator) with the ''grouping operator'',<ref>{{cite web|url=https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Grouping|title=Grouping operator|publisher=Mozilla Developer Network}}</ref> i.e. in parentheses, to explicitly tell the parser to expect an expression. Otherwise, in most situations, when the parser encounters the <code>function</code> keyword, it treats it as a function declaration (statement), and not as a function expression.<ref>{{cite book|last=Zakas|first=Nicholas|title=Maintainable JavaScript|year=2012|publisher=O'Reilly|isbn=9781449327682|pages=44}}</ref><ref>{{cite web|last=Crockford|first=Douglas|authorlink=Douglas Crockford|title=Code Conventions for the JavaScript Programming Language|url=http://javascript.crockford.com/code.html|accessdate=3 February 2013}}</ref>

<syntaxhighlight lang="JavaScript">

(function () { … })();

(function () { … }()); // Douglas Crockford's style

</syntaxhighlight>

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-function () { … }();

+function () { … }();

void function () { … }(); // Dr. Axel Rauschmayer example

</syntaxhighlight>