Create GUID / UUID in JavaScript

guid.js

//For an rfc4122 version 4 compliant solution, this one-liner(ish) solution is the most compact I could come up with
//http://stackoverflow.com/a/2117523
'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
    return v.toString(16);
});

//http://guid.us/GUID/JavaScript
function S4() {
    return (((1+Math.random())*0x10000)|0).toString(16).substring(1); 
}
 
// then to call it, plus stitch in '4' in the third group
guid = (S4() + S4() + "-" + S4() + "-4" + S4().substr(0,3) + "-" + S4() + "-" + S4() + S4() + S4()).toLowerCase();
alert(guid);