function TIMER()
{
   this.DateStart = null;
   this.DateStop  = null;

   this.Start = function()
     {
        this.DateStart = new Date();   
     }

   this.Stop = function()
     {
        this.DateStop = new Date(); 

        var Difference = Date.parse(this.DateStop)+this.DateStop.getMilliseconds()-
                         (Date.parse(this.DateStart)+this.DateStart.getMilliseconds()); 

        this.DateStart = null;
        this.DateStop  = null;

        return Difference;
     }
}

var objTimer = new TIMER();