UTM detection and time zone change

Date.prototype.changeTime= function(currentUTM, switchtoUTM){
    this.setHours(this.getHours()+inc_value);
    return this;
}

// My current location: EST - USA East coast is  UTM -5 hours
// The Location I want to get the Time of is CET – Central European Time UTM +1 hours


var currentdate = new Date(); 
var currentDTString  = "You're current time: " + currentdate.getDate() + "/"
                + (currentdate.getMonth()+1)  + "/" 
                + currentdate.getFullYear() + " @ "  
                + currentdate.getHours() + ":"  
                + currentdate.getMinutes() + ":" 
                + currentdate.getSeconds();
 alert(" " +datetime );