Do you know something about this Ajax method?

Hi all...
I’m trying to implement a simple Ajax page with a method I read few days ago, but I can’t find what’s the page I was reading about an interesting method.
Perhaps someone have it in his/her bookmarks.

It was an xmlhttprequest tutorial (with included JS file), but alike the other 1000 tutorials around it degrades beautifully in a simple list of classic links and not in a useless bunch of "onclick=". If I can remember correctly it envolves setting a class on this links, something like "targetTo_IDofElement", which JS will intercept and use to update the target.
Sorry but JS is very far from me .

Thanks for the help.