round up/ round down a momentjs moment to nearest minute

Question

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

Answer 1

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/

Answer 2

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

Answer 3

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/moment@2.24.0/min/moment.min.js"></script>

Answer 4

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