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Trying to figure out what this means in javascript.

(function(document) { ... } )(document);

It is isn't using jQuery, so is this just a javascript way of making this wait till document is ready to execute? Thanks.

hunterc
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  • A general pattern is to use immediately invoked function expressions `(function () { /* code here */ }());` to create nested scopes (variable environments). So, if you have a block of code within a whole lot of other code, and that block needs a bunch of variables, it makes sense to use that pattern to prevent those variables from polluting the outer code. – Šime Vidas Sep 06 '13 at 14:47

4 Answers4

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This won't wait for the document to be ready, this will execute the content of the function immediately. Putting the function definition in parenthesis makes it an expression, which returns a value being the function, making it directly executable. This pattern is called an Immediately-Invoked Function Expression (IIFE).

This is probably used in conjunction with a minifier like the Closure Compiler.

Inside the function, document is a local variable. This makes it possible for the minifier to reduce its name to a one or two character name.

Note also that all variables defined inside the function will be local : they won't leak in the global scope, which may be interesting if this is only part of the script.

Denys Séguret
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This creates an anonymous function that takes a single argument, and immediately calls it passing document as the argument.

NPE
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This:

function(document) { ... }

creates a function taking one paremeter.

This:

(function(document) { ... })

makes it (the code, not the function) a valid expression. See here.

This:

(function(document) { ... } )(document);

calls that function with document as a parameter.

It's a basic modularization pattern. In different environments you could've passed some other object instead of document, but nothing inside that function has to know bout it.

Community
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soulcheck
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This is called self-executed function. It evaluates the anonymous function taking a parameter called document with that parameter passed in.

zs2020
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