[javascript] 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?

Maybe something like this?

var d = new Date();_x000D_
var v = new Date();_x000D_
v.setMinutes(d.getMinutes()+30);_x000D_
_x000D_
console.log(v)

You should get the value of the current date to get the date with (ms) and add (30 * 60 *1000) to it. Now you have (current date + 30 min) with ms

console.log('with ms', Date.now() + (30 * 60 * 1000))_x000D_
console.log('new Date', new Date(Date.now() + (30 * 60 * 1000)))

Other solution:

var dateAv = new Date();
var endTime = new Date(dateAv.getFullYear(), dateAv.getMonth(), dateAv.getDate(), dateAv.getHours(), dateAv.getMinutes() + 30);
          

I always create 7 functions, to work with date in JS:
addSeconds, addMinutes, addHours, addDays, addWeeks, addMonths, addYears.

You can see an example here: http://jsfiddle.net/tiagoajacobi/YHA8x/

How to use:

var now = new Date();
console.log(now.addMinutes(30));
console.log(now.addWeeks(3));

These are the functions:

Date.prototype.addSeconds = function(seconds) {
  this.setSeconds(this.getSeconds() + seconds);
  return this;
};

Date.prototype.addMinutes = function(minutes) {
  this.setMinutes(this.getMinutes() + minutes);
  return this;
};

Date.prototype.addHours = function(hours) {
  this.setHours(this.getHours() + hours);
  return this;
};

Date.prototype.addDays = function(days) {
  this.setDate(this.getDate() + days);
  return this;
};

Date.prototype.addWeeks = function(weeks) {
  this.addDays(weeks*7);
  return this;
};

Date.prototype.addMonths = function (months) {
  var dt = this.getDate();
  this.setMonth(this.getMonth() + months);
  var currDt = this.getDate();
  if (dt !== currDt) {  
    this.addDays(-currDt);
  }
  return this;
};

Date.prototype.addYears = function(years) {
  var dt = this.getDate();
  this.setFullYear(this.getFullYear() + years);
  var currDt = this.getDate();
  if (dt !== currDt) {  
    this.addDays(-currDt);
  }
  return this;
};

The easiest way to solve is the to recognize that in javascript dates are just numbers. It starts 0 or 'Wed Dec 31 1969 18:00:00 GMT-0600 (CST). Every 1 represents a millisecond. You can add or subtract milliseconds by getting the value and instantiating a new date using that value. You can manage it pretty easy with that mind.

const minutesToAdjust = 10;
const millisecondsPerMinute = 60000;
const originalDate = new Date('11/20/2017 10:00 AM');
const modifiedDate1 = new Date(originalDate.valueOf() - (minutesToAdjust * millisecondsPerMinute));
const modifiedDate2 = new Date(originalDate.valueOf() + (minutesToAdjust * millisecondsPerMinute));

console.log(originalDate); // Mon Nov 20 2017 10:00:00 GMT-0600 (CST)
console.log(modifiedDate1); // Mon Nov 20 2017 09:50:00 GMT-0600 (CST)
console.log(modifiedDate2); // Mon Nov 20 2017 10:10:00 GMT-0600 (CST)

Here is the ES6 version:

let getTimeAfter30Mins = () => {
  let timeAfter30Mins = new Date();
  timeAfter30Mins = new Date(timeAfter30Mins.setMinutes(timeAfter30Mins.getMinutes() + 30));
};

Call it like:

getTimeAfter30Mins();

You could do this:

let thirtyMinutes = 30 * 60 * 1000; // convert 30 minutes to milliseconds_x000D_
let date1 = new Date();_x000D_
let date2 = new Date(date1.getTime() + thirtyMinutes);_x000D_
console.log(date1);_x000D_
console.log(date2);

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.

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]());
}

Use an existing library known to handle the quirks involved in dealing with time calculations. My current favorite is moment.js.

<script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.13.0/moment.js"></script>
<script>
 var now = moment(); // get "now"
 console.log(now.toDate()); // show original date
 var thirty = moment(now).add(30,"minutes"); // clone "now" object and add 30 minutes, taking into account weirdness like crossing DST boundries or leap-days, -minutes, -seconds.
 console.log(thirty.toDate()); // show new date
</script>

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));

For the lazy like myself:

Kip's answer (from above) in coffeescript, using an "enum", and operating on the same object:

Date.UNIT =
  YEAR: 0
  QUARTER: 1
  MONTH: 2
  WEEK: 3
  DAY: 4
  HOUR: 5
  MINUTE: 6
  SECOND: 7
Date::add = (unit, quantity) ->
  switch unit
    when Date.UNIT.YEAR then @setFullYear(@getFullYear() + quantity)
    when Date.UNIT.QUARTER then @setMonth(@getMonth() + (3 * quantity))
    when Date.UNIT.MONTH then @setMonth(@getMonth() + quantity)
    when Date.UNIT.WEEK then @setDate(@getDate() + (7 * quantity))
    when Date.UNIT.DAY then @setDate(@getDate() + quantity)
    when Date.UNIT.HOUR then @setTime(@getTime() + (3600000 * quantity))
    when Date.UNIT.MINUTE then @setTime(@getTime() + (60000 * quantity))
    when Date.UNIT.SECOND then @setTime(@getTime() + (1000 * quantity))
    else throw new Error "Unrecognized unit provided"
  @ # for chaining

Just another option, which I wrote:

DP_DateExtensions Library

It's overkill if this is all the date processing that you need, but it will do what you want.

Supports date/time formatting, date math (add/subtract date parts), date compare, date parsing, etc. It's liberally open sourced.

I know that the topic is way too old. But I am pretty sure that there are some developpers who still need this, so I made this simple script for you. I hope you enjoy it!

Hello back, It's 2020 and I've added some modification hope it will help a lot better now!

function strtotime(date, addTime){
  let generatedTime=date.getTime();
  if(addTime.seconds) generatedTime+=1000*addTime.seconds; //check for additional seconds 
  if(addTime.minutes) generatedTime+=1000*60*addTime.minutes;//check for additional minutes 
  if(addTime.hours) generatedTime+=1000*60*60*addTime.hours;//check for additional hours 
  return new Date(generatedTime);
}

Date.prototype.strtotime = function(addTime){
  return strtotime(new Date(), addTime); 
}

let futureDate = new Date().strtotime({
    hours: 16, //Adding one hour
    minutes: 45, //Adding fourty five minutes
    seconds: 0 //Adding 0 seconds return to not adding any second so  we can remove it.
});

<button onclick="console.log(futureDate)">Travel to the future</button>

it is simple as it is;

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

Here is my one-liner:

console.log('time: ', new Date(new Date().valueOf() + 60000))

Here is the IsoString version:

console.log(new Date(new Date().setMinutes(new Date().getMinutes() - (30))).toISOString());

var d1 = new Date (),
    d2 = new Date ( d1 );
d2.setMinutes ( d1.getMinutes() + 30 );
alert ( d2 );