$ in IFrame

Prototype $ method works well on parent page. However, if it has an IFrame, what happend to $ method? I have tested it here and here

One of my friend suggested to overcome the situation and shared me the code by which you can extend $ method of prototype in Iframe. He could not tell me the source but after searching a lot, I found that from here

 Demonstration

 Code I used here

    <script type="text/javascript">
        // Extend prototype's Method avaialble for IFrame
        Prototype.extendFrame = function(element) {
            element = $(element);
            for (var m in Element.Methods) {
                if (Object.isFunction(Element.Methods[m])) {
                    element.contentWindow.Element.prototype[m] = Element.Methods[m].methodize();
                }
            }
        }
    </script>
    

 Finally what I understand

Now, I am happy that I can use prototype $ method in IFRAME using the above method.