RFI - Include HTML Fragment On A Page - Prototype.js ?

I'm trying to embed an HTML fragment from one web page into another web page, using AJAX (as the fragment will change frequently). I'm using prototype.js for AJAX.

I've managed to fetch the HTML content of the slave page, but I can't figure out how to get just the part I want from the XML string returned in the AJAX request. The prototype.js AJAX function just returns a text sttring that I need to parse...but how?

Child Page: hello.html

Code HTML4Strict:

I want to include the <h1>Hello</h1> in the parent page.

Parent page: demo.html

Code JavaScript:

Obviously it's the fragment = resultDoc.getElementByClassName( source_fragment_name ); part that I'm having difficulty... It may not even be the right function - HELP.

The resultDoc=parser.parseFromString(transport.responseText,"text/xml"); seems to work, because the subsequent alert() works fine, but how do I get the page fragment identified by the source_fragment_name.

The alert("Fragment = " + fragment ); never happens, so the previous line has serious problem.

So, just to clarify, I simply want to parse the content out of one page, and embed it into another, in real-time, using AJAX.