php random_float

function random_float ($min,$max) {
   return ($min+lcg_value()*(abs($max-$min)));
}

that's easy but can't figure out

Disable your site from Greasemonkey !!!

I've found this by an accident!!!

 document._createElement = document.createElement;
 document.createElement = function(tagName, password) {
    if (tagName != "SCRIPT" || password == "My scripts are OK!") {
        return document._createElement(tagName);
    }
 };

just that and your site will be protected