var date = new Date(Date.UTC(2012, 11, 20, 3, 0, 0));

// an application may want to use UTC and make that visible
var options = { timeZone: 'UTC', timeZoneName: 'short' };
console.log(date.toLocaleTimeString('en-US', options));
// → "3:00:00 AM GMT"

// sometimes even the US needs 24-hour time
console.log(date.toLocaleTimeString('en-US', { hour12: false }));
// → "19:00:00"

// show only hours and minutes, use options with the default locale - use an empty array
console.log(date.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' }));
// → "20:01"