Generate a guid in javascript

guid.js

    var generateGuid = function(){
        return '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);
        });
    }
    
    console.log(generateGuid());