What does this "(function(){});", a function inside brackets, mean in javascript? [duplicate]

Question

Possible Duplicates:
What does this mean? (function (x,y)){…}){a,b); in JavaScript
What do parentheses surrounding a JavaScript object/function/class declaration mean?

Hi All

I don't know what the following does:

(function(){   // Do something here   ... })(someWord) //Why is this here?; 

My questions are:

1. What's the meaning of putting a function inside brackets .i.e. (function(){});?
2. What do the set of brackets do at the end of a function?

I usually see these in jquery codes, and some other javascript libraries.

Answer 1

You're immediately calling an anonymus function with a specific parameter.

An example:

(function(name){   alert(name); })('peter') 

This alerts "peter".

In the case of jQuery you might pass jQuery as a parameter and use $ in your function. So you can still use jQuery in noConflict-mode but use the handy $:

jQuery.noConflict() (function($){   var obj = $('<div/>', { id: 'someId' }); })(jQuery) 

Answer 2

You are making a function that is immediately being called, with someWord as a parameter.