function create_UUID(){  
        var dt = new Date().getTime();  
        var uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {  
            var r = (dt + Math.random()*16)%16 | 0;  
            dt = Math.floor(dt/16);  
            return (c=='x' ? r :(r&0x3|0x8)).toString(16);  
        });  
        return uuid;  
    }  
      
    console.log(create_UUID());