Question

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What is the difference between these jQuery ready functions?

I have always used:

$(document).ready(function (){
    //Code goes here
});

And inserted my jQuery/JavaScript code therein (so that it waits on the html page to be fully loaded before running any code).

Lately, I have seen this:

jQuery(function($){
    //Code goes here
});

I have searched for what the difference is here (mainly what the ‘jQuery’ part is all about).

My questions:

• What does the jQuery part of the latter code block do, if anything?
• What is the ‘($)’ argument doing for that function?
• Is there even a difference (other than making the page wait to be loaded) between my two code block examples?

Answer 1

The main difference is the closure around the $ variable. The first snippet assumes that the $ variable has not been released (by using .noConflict() or if another library you are using also makes use of $ but not as the jQuery variable).

The second implementation is safer because it doesn’t make any assumptions but allows your internal code to safely use the $ variable by making it a parameter.