Create GUID in JavaScript

Case 1:

jquery.guid.js

var guid = jQuery.Guid.New()

but sometimes, it return an error Guid is undefined, etc ...

Case 2: 

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);

 

Source:

http://guid.us/GUID/JavaScript