what is( function($){.....})(jQuery) that often used in the making of jquery plugin

Question

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a simple question on jquery closure

I often see the code of jquery plugin consist this code, Can I know what it is? and what the purpose for?

Answer 1

Knowing little about jQuery, but something about JavaScript, I'd guess this declares an anonymous function that receives one argument (accessible using $ in the body of the function) and immediately calls this function, passing the jQuery object as argument.

Answer 2

How jQuery plugins usually work is that they make a function that adds the plugin to jQuery, and then immediately call that function so the plugin is installed. The notation

(function($) { ..code... })(jQuery)

makes a nameless function and then calls that function, passing the jQuery object as an argument. And then somewhere in the code of that function, you should find a

$.fn.newPlugin = ...

This adds the plugin into jQuery. This is done so that no conflicts are created; using this notation, no function names or variable names are actually declared.