How to add 30 minutes to a JavaScript Date object?

Question

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

Answer 1

it is simple as it is;

let initial_date = new Date;
let added30Min = new Date(initial_date.getTime() + (30*60*1000);

Answer 2

I feel many of the answers here are lacking a creative component, very much needed for time travel computations. I present my solution for a temporal translation of 30 minutes.

(jsfiddle here)

function fluxCapacitor(n) {
    var delta,sigma=0,beta="ge";
    (function(K,z){

        (function(a,b,c){
            beta=beta+"tT";
            switch(b.shift()) {
                case'3':return z('0',a,c,b.shift(),1);
                case'0':return z('3',a,c,b.pop());
                case'5':return z('2',a,c,b[0],1);
                case'1':return z('4',a,c,b.shift());
                case'2':return z('5',a,c,b.pop());
                case'4':return z('1',a,c,b.pop(),1);
            }
        })(K.pop(),K.pop().split(''),K.pop());
    })(n.toString().split(':'),function(b,a,c,b1,gamma){
       delta=[c,b+b1,a];sigma+=gamma?3600000:0; 
       beta=beta+"im";
    });
    beta=beta+"e";
    return new Date (sigma+(new Date( delta.join(':')))[beta]());
}

Answer 3

Using a Library

If you are doing a lot of date work, you may want to look into JavaScript date libraries like Datejs or Moment.js. For example, with Moment.js, this is simply:

var newDateObj = moment(oldDateObj).add(30, 'm').toDate();

Vanilla Javascript

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);
}

^{And just in case this is not obvious, the reason we multiply minutes by 60000 is to convert minutes to milliseconds.}

Be Careful with Vanilla Javascript. Dates Are Hard!

You may think you can add 24 hours to a date to get tomorrow's date, right? Wrong!

addMinutes(myDate, 60*24); //DO NOT DO THIS

It turns out, 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:

const NOV = 10; //because JS months are off by one...
addMinutes(new Date(2014, NOV, 2), 60*24); //In USA, prints 11pm on Nov 2, not 12am Nov 3!

This is why using one of the afore-mentioned libraries is a safer bet if you have to do a lot of work with this.

Below is a more generic version of this function that I wrote. I'd still recommend using a library, but that may be overkill/impossible for your project. The syntax is modeled after MySQL DATE_ADD function.

/**
 * Adds time to a date. Modelled after MySQL DATE_ADD function.
 * Example: dateAdd(new Date(), 'minute', 30)  //returns 30 minutes from now.
 * https://stackoverflow.com/a/1214753/18511
 * 
 * @param date  Date to start with
 * @param interval  One of: year, quarter, month, week, day, hour, minute, second
 * @param units  Number of units of the given interval to add.
 */
function dateAdd(date, interval, units) {
  if(!(date instanceof Date))
    return undefined;
  var ret = new Date(date); //don't change original date
  var checkRollover = function() { if(ret.getDate() != date.getDate()) ret.setDate(0);};
  switch(String(interval).toLowerCase()) {
    case 'year'   :  ret.setFullYear(ret.getFullYear() + units); checkRollover();  break;
    case 'quarter':  ret.setMonth(ret.getMonth() + 3*units); checkRollover();  break;
    case 'month'  :  ret.setMonth(ret.getMonth() + units); checkRollover();  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;
}

Working jsFiddle demo.

Answer 4

Maybe something like this?

var d = new Date();
var v = new Date();
v.setMinutes(d.getMinutes()+30);

console.log(v)

Answer 5

This is what I do which seems to work quite well:

Date.prototype.addMinutes = function(minutes) {
    var copiedDate = new Date(this.getTime());
    return new Date(copiedDate.getTime() + minutes * 60000);
}

Then you can just call this like this:

var now = new Date();
console.log(now.addMinutes(50));

Answer 6

var oldDateObj = new Date();
var newDateObj = new Date();
newDateObj.setTime(oldDateObj.getTime() + (30 * 60 * 1000));
console.log(newDateObj);