jQuery Forum

1. It's executed immediately. It's more than an anonymous function - it's a self-calling anonymous function.

2. Nope. If you want $(document).ready(), you have to put that inside it.

3. Anything declared with "var" inside the function is private to that function and cannot be accessed from outside it. That's actually the main reason for using self-calling anonymous functions: to provide a local scope where you can set up functions and variable without cluttering the global namespace.

You can "export" something from inside the private scope by either not declaring it var, in which it will default to being global, or by attaching it to the global window object or any other global object.

For example, the standard pattern for creating jQuery plugins is :

1. (function ($) {
2.       $.fn.doSomething = function () {}; // attach func to global jQuery object
3. }(jQuery));

I see. So I still have to have the $(document).ready() function inside my anonymous function calls just be sure that my target element is present before script execution. Or since my script tags are at the bottom of my page (not on the head) maybe i will not be needing this anymore..

Rob - everything you say is right. I was just trying to keep it simple.

A self-calling anonymous function is executed as soon as it is reached in the normal order of evaluation, as opposed to an event handler hollaback function.

Vars can be accessed from closures, but they are are lexically inside the containing function, even if they get used elsewhere. And explaining closures to someone asking a basic question about self-calling functions seemed a bit overkill.

And yes, default globals are bad. I can't fault you there. But the guy needed a primer on JavaScript scoping and understanding that variables are global by default seems like a big part of that. But you're right, I should have put flashing lights and DANGER signs around that comment.

And just to wrench this back on topic, for the benefit of the original poster, if you do need to create a global variable ("export" seems like a perfectly good description of the operation to me :P), then wrapping your code in a self-calling anonymous function and passing in "window" is a perfectly good way to do it:

1. (function (window) {
2.       var myBrilliantThingy;
3.       // assemble myBrilliantThingy
4.       window.myBrilliantThingy = myBrilliantThingy;
5. }(window));

In fact, you can remove the assumption that you're in a browser:

1. (function (global) {
2.       var myBrilliantThingy;
3.       // assemble myBrilliantThingy
4.       global.myBrilliantThingy = myBrilliantThingy;
5. }(this));