Run document.ready only if jquery is loaded

Question

I have this code in a global JS file.

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

Unfortunately there are pages that include this file but doesn't include the jquery file. So I get errors:

Message: The value of the property '$' is null or undefined, 
not a Function object

How do I run document.ready() only if JQuery file is loaded.

Answer 1

if(window.jQuery) {
    $(document).ready(function() {
        DoStuff();
    });
}

UPDATE

Check for window.jQuery instead of just jQuery. This should circumvent the "not defined" error.

Answer 2

You would test for the existence of jQuery first:

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