I could be incorrect, but I think he means implement the feature on top of 1.6, not the system itself. The web example would be getElementsByClassName: func

I could be incorrect, but I think he means implement the feature on top of 1.6, not the system itself. The web example would be getElementsByClassName: function getElementsByClassName(node,classname) { if (node.getElementsByClassName) return node.getElementsByClassName(classname); else { // your custom function } } (example from quirksmode.org)