How to add 30 minutes to a JavaScript Date object?

I'd like to get a Date object which is 30 minutes later than another Date object. How do I do it with JavaScript?

Solution :

If you are doing a lot of date work, you may want to look into JavaScript date libraries like Datejs or Moment.js
This is like chaos's answer, but in one line:
var newDateObj = new Date(oldDateObj.getTime() + diff*60000);
Where diff is the difference in minutes you want from oldDateObj's time. It can even be negative.
Or as a reusable function, if you need to do this in multiple places:
function addMinutes(date, minutes) {
    return new Date(date.getTime() + minutes*60000);
}

A word of caution

Do not use the above to try add days. For example:
addMinutes(myDate, 60*24); //DO NOT DO THIS
If the user observes daylight saving time, a day is not necessarily 24 hours long--there is one day a year that is only 23 hours long, and one day a year that is 25 hours long. For example, in most of the United States and Canada, 24 hours after midnight, Nov 2, 2014, is still Nov 2:
addMinutes(new Date('2014-11-02'), 60*24); //In USA, prints 11pm on Nov 2, not 12am Nov 3!
Instead, here is a more generic version of this function that I wrote. The syntax is modeled after MySQL DATE_ADD function.
function dateAdd(date, interval, units) {
  var ret = new Date(date); //don't change original date
  switch(interval.toLowerCase()) {
    case 'year'   :  ret.setFullYear(ret.getFullYear() + units);  break;
    case 'quarter':  ret.setMonth(ret.getMonth() + 3*units);  break;
    case 'month'  :  ret.setMonth(ret.getMonth() + units);  break;
    case 'week'   :  ret.setDate(ret.getDate() + 7*units);  break;
    case 'day'    :  ret.setDate(ret.getDate() + units);  break;
    case 'hour'   :  ret.setTime(ret.getTime() + units*3600000);  break;
    case 'minute' :  ret.setTime(ret.getTime() + units*60000);  break;
    case 'second' :  ret.setTime(ret.getTime() + units*1000);  break;
    default       :  ret = undefined;  break;
  }
  return ret;
}

http://stackoverflow.com/questions/1197928/how-to-add-30-minutes-to-a-javascript-date-object/1214753#1214753

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