jquery anonymous function declaration meanings

Question

Are the following assumptions accurate?

1) execute immediately

(function(){ })(); 

2) execute on document ready

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

3) shorthand for on document ready

$(function(){ }); 

4) alternative shorthand for on document ready for avoiding cross script conflicts

(function($) { })(jQuery); 

Answer 1

Yes your definitions are correct, for the first 3 :)

Though, unless you need a closure, a statement will execute immediately, no reason to wrap it like #1 has (there are certainly plenty of valid times you need a closure, just noting if you don't...it's superfluous).

Number 4 however is not correct, (function($) { })(jQuery); is not tied to any event, it's just a closure so that $ === jQuery inside of it, so you can use the $ shortcut:

(function($) {    //You may use $ here instead of jQuery and it'll work...even if $ means   //something else outside of this closure, another library shortcut for example })(jQuery);