var date = new Date(Date.UTC(2012, 11, 20, 3, 0, 0));
// formats below assume the local time zone of the locale;
// America/Los_Angeles for the US
// US English uses 12-hour time with AM/PM
console.log(date.toLocaleTimeString('en-US'));
// "7:00:00 PM"
// British English uses 24-hour time without AM/PM
console.log(date.toLocaleTimeString('en-GB'));
// "03:00:00"