Got it !
Wanted to force the date shown = server date, no mattter the local settings (UTC).
My server is GMT-6 --> new Date().getTimezoneOffset() = 360.
myTZO = 360;
myNewDate=new Date(myOldDateObj.getTime() + (60000*(myOldDateObj.getTimezoneOffset()-myTZO)));
alert(myNewDate);