Calculating timespans in Javascript/ECMAScript

Question

I've got a variable that holds a number of miliseconds which represents the timespan from now to a specified point in the future.

I want to convert this milisecond figure into a timespan value I can display to users.

I know I can do this the native way with modulo arithmetic and manually displaying the result to the user, but I want to do this using the Date() API built-in to Javascript/ECMAScript.

This is how I generate it:

var timespanInMS = timeInFuture.getTime() - now.getTime();
var diff = new Date( timespanInMS );

alert( "Hours: " + diff.getHours() + " Minutes: " + diff.getMinutes() );

However this only works when the user's computer is in the UTC timezone. If they're in Pacific (UTC-8) then the value of 'diff' is off by 16 hours (even though the timespanInMS figure is the same).

Thanks

Answer 1

Perhaps getUTCHours and getUTCMinutes might work? See https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Date for more information.