Matthias Miller's DOMReady hack creates a new script element using document.write(). After its onload event has fired, however, this element remains part of the DOM -- it will be discovered by $('script') or $('head>*'), for example.

Since this is a permanent modification of the DOM, scripts which rely on a particular order or number of elements will throw exceptions. Assumptions about the generated DOM are often unreliable anyway, but it is not hard to imagine a situation where scripts could be broken by this.

The bug is trivial to fix, however: the element just needs to delete itself once it has become unnecessary.

We can change this section:

script.onreadystatechange = function() {

if ( this.readyState == "complete" )

jQuery.ready();

};

...to this:

script.onreadystatechange = function() {

if ( this.readyState != "complete" ) return;

this.parentNode.removeChild(this);

jQuery.ready();

};

...and then the problem is solved.