round up/ round down a momentjs moment to nearest minute

How do you round up/ round down a momentjs moment to nearest minute?

I have checked the docs, but there doesn't appear to be a method for this.

Note that I do not want a string rounded to the nearest minute, I want a moment returned (or modified in place, either is fine). I prefer not to have to convert to a string, and the convert back too.

Thanks.

---

As requested, here is some code:

var now = new moment(new Date());

if (now.seconds() > 0) {
    now.add('minutes', -1);
}

now.seconds(0);

as you can see, I have managed to manually round down the moment here, but it seems rather hacky. Just after a more elegant way of accomplishing this.

To round up, you need to add a minute and then round it down. To round down, just use the startOf method.

Note the use of a ternary operator to check if the time should be rounded (for instance, 13:00:00 on the dot doesn't need to be rounded).

Round up/down to the nearest minute

var m = moment('2017-02-17 12:01:01');
var roundDown = m.startOf('minute');
console.log(roundDown.toString()); // outputs Tue Feb 17 2017 12:01:00 GMT+0000

var m = moment('2017-02-17 12:01:01');
var roundUp = m.second() || m.millisecond() ? m.add(1, 'minute').startOf('minute') : m.startOf('minute');
console.log(roundUp.toString());  // outputs Tue Feb 17 2017 12:02:00 GMT+0000

Round up/down to the nearest hour

var m = moment('2017-02-17 12:59:59');
var roundDown = m.startOf('hour');
console.log(roundDown.toString()); // outputs Tue Feb 17 2017 12:00:00 GMT+0000

var m = moment('2017-02-17 12:59:59');
var roundUp = m.minute() || m.second() || m.millisecond() ? m.add(1, 'hour').startOf('hour') : m.startOf('hour');
console.log(roundUp.toString());  // outputs Tue Feb 17 2017 13:00:00 GMT+0000

Partial answer:

To round down to nearest moment minute:

var m = moment();
m.startOf('minute');

However, the equivalent for rounding up, endOf, doesn't quite give the expected result.

Rounding to the nearest hour can be achieved by adding half an hour and then run .startOf('hour'). This is the same for any time measurement.

var now = moment();
// -> Wed Sep 30 2015 11:01:00
now.add(30, 'minutes').startOf('hour'); // -> Wed Sep 30 2015 11:31:00
// -> Wed Sep 30 2015 11:00:00

var now = moment();
// -> Wed Sep 30 2015 11:31:00
now.add(30, 'minutes').startOf('hour'); // -> Wed Sep 30 2015 12:01:00
// -> Wed Sep 30 2015 12:00:00

The roundTo feature could make it into a future release.

Examples:

moment().roundTo('minute', 15); // output: 12:45
moment().roundTo('minute', 15, 'down'); // output: 12:30

#Rounding Down

Easy. As stated by many others, just use Moment.startOf:

var roundDown = moment('2015-02-17 12:59:59').startOf('hour');
roundDown.format('HH:mm:SS'); // 12:00:00

Importantly, this also works as expected:

var roundDown = moment('2015-02-17 12:00:00').startOf('hour');
roundDown.format('HH:mm:SS'); // 12:00:00

#Rounding Up

Slightly trickier, if we want to round up with a proper ceiling function: for example, when rounding up by hour, we want 12:00:00 to round up to 12:00:00.

##This does not work

var roundUp = moment('2015-02-17 12:00:00').add(1, 'hour').startOf('hour');
roundUp.format('HH:mm:SS'); // ERROR: 13:00:00

Solution

function roundUp(momentObj, roundBy){
  return momentObj.add(1, roundBy).startOf(roundBy);
}


var caseA = moment('2015-02-17 12:00:00');
roundUp(caseA, 'minute').format('HH:mm:SS'); // 12:00:00

var caseB = moment('2015-02-17 12:00:00.001');
roundUp(caseB, 'minute').format('HH:mm:SS'); // 12:01:00

var caseC = moment('2015-02-17 12:00:59');
roundUp(caseC, 'minute').format('HH:mm:SS'); // 12:01:00

A more precise answer:

t.add(30, 'seconds').startOf('minute')

Case1: Rounding down if seconds < 30

t = moment(); //12:00:05
t.add(30, 'seconds').startOf('minute') //12:00:00

Case2: Rounding up if seconds >= 30

t = moment(); //12:00:33
t.add(30, 'seconds').startOf('minute') //12:01:00

I was searching for this same question and found a better solution: Use the third parameter in diff() function:

moment("2019-05-02 17:10:20").diff("2019-05-02 17:09:30","minutes",true)

By setting third parameter to true, you get the raw value as response that you can round by yourself using Math.round()

See JSFiddle: https://jsfiddle.net/2wqs4o0v/3/

This solution worked for me;

function round_up_to_nearest_hour(date = new Date()) {
   return moment(date).add(59, 'minutes').startOf('hour').toDate();
}

Just another possibility:

const now = moment();
// -> Wed Sep 30 2015 11:57:20 GMT+0200 (CEST)
now.add(1, 'm').startOf('minute');
// -> Wed Sep 30 2015 11:58:00 GMT+0200 (CEST)

The simplest solution so far:

function floor(time, floorBy = 'minute') {
  return time.startOf(floorBy);
}

function ceil(time, ceilBy = 'minute') {
  return time.subtract(1, 'millisecond').add(1, ceilBy).startOf(ceilBy);
}

// The solution is above. The code below is an optional test:

console.log(
  floor(moment('2019-01-01 12:00:00.000')).format('H:mm:ss.SSS') === '12:00:00.000',
   ceil(moment('2019-01-01 12:00:00.000')).format('H:mm:ss.SSS') === '12:00:00.000',
  floor(moment('2019-01-01 12:00:00.001')).format('H:mm:ss.SSS') === '12:00:00.000',
   ceil(moment('2019-01-01 12:00:00.001')).format('H:mm:ss.SSS') === '12:01:00.000',
  floor(moment('2019-01-01 12:15:16.876'), 'hour'  ).format('H:mm:ss.SSS') === '12:00:00.000',
   ceil(moment('2019-01-01 12:15:16.876'), 'hour'  ).format('H:mm:ss.SSS') === '13:00:00.000',
  floor(moment('2019-01-01 12:59:59.999'), 'second').format('H:mm:ss.SSS') === '12:59:59.000',
   ceil(moment('2019-01-01 12:59:59.999'), 'second').format('H:mm:ss.SSS') === '13:00:00.000',
  floor(moment('2019-01-01 12:00:00.025'), 'ms'    ).format('H:mm:ss.SSS') === '12:00:00.025',
   ceil(moment('2019-01-01 12:00:00.025'), 'ms'    ).format('H:mm:ss.SSS') === '12:00:00.025'
);

<script src="//cdn.jsdelivr.net/npm/[email protected]/min/moment.min.js"></script>

a better (and simple) approach will be -

moment('2021-07-22 14:56:58')
        .startOf('hour')
        .add(1, 'hour')
        // optional: .format('MMMM D, YYYY (h:mm A)')
//output: July 22, 2021 (3:00 PM)

Round up to the next hour

a simple approach will be -

moment('2021-07-22 14:56:58')
        .startOf('hour')
        .add(1, 'hour')
        // optional: .format('MMMM D, YYYY (h:mm A)')
//output: July 22, 2021 (3:00 PM)