How to redefine JavaScript native functions

<body> <center>Sorry you do not have frames enabled. Here is the link of the tutorial:<br> <a href="http://www.cosminsanda.eu/how-to-redefine-javascript-native-functions/2008/01/24/">http://www.cosminsanda.eu/how-to-redefine-javascript-native-functions/2008/01/24/</a></center> </body>