Here are your codes...
<!--Place this script in the HEAD section--> <script language="JavaScript"> var n3 = false;function on3(name) { document[name].src = eval(name + "on.src"); } function off3(name) { document[name].src = eval(name + ".src"); } n3 = true; function on(name) { if (n3) on3(name); } function off(name) { if (n3) off3(name); } </script> <--Place this part in the BODY section of your html document.-->