CODEWITHSUNDEEP
javascriptmomentjs
user3568719
user3568719

Reputation: 1056

minutes between a date and a string time

I have a starting hour given in string.

let opens = '08:00';

I want to measure the difference in minutes for various dates.

let date1 = moment('1945.10.20 17:30');
let date2 = moment('1970.01.08 12:00');
// should result 570 (9.5h) and 240 (4h)

I was naive enough to try

moment(opens, 'HH:mm').diff(date1, 'm');

but I realized that it would make a date for the current day's hour.

Upvotes: 0

Views: 66

Answers (3)

David Sherret
David Sherret

Reputation: 106640

Get a moment object on the same day, but with the hours you want. From there do the comparison. If you know the format of opens will always be HH:mm then you can do this:

let opens = '08:00';
let opensTime = moment(opens, 'HH:mm');
let date1 = moment('1945.10.20 17:30', 'YYYY.MM.DD HH:mm');
let openDate1 = date1.clone().set({
    hour: opensTime.hour(),
    minute: opensTime.minute()
});

Then compare:

date1.diff(openDate1, 'm') === 570;

Alternatively, you could just do a split on opens—opens.split(":")—to get the hour and minute.

Upvotes: 2

IMTheNachoMan
IMTheNachoMan

Reputation: 5811

Can you modify the opens variable?

let date1 = moment(new Date('1945.10.20 17:30'));
let date2 = moment(new Date('1970.01.08 12:00'));

function timeDifference(end, opensHour, opensMinute) {
  var start = end.clone().set({
    "hour": opensHour,
    "minute": opensMinute
  });

  return {
    "start": start,
    "end": end,
    "difference": end.diff(start, "minutes")
  };
}

console.log(timeDifference(date1, 8, 0));
console.log(timeDifference(date2, 8, 0));
<script src="http://momentjs.com/downloads/moment.js"></script>

Essentially what you need to do is, once you have the end dates, create a new moment with the same date but your opens start time. Then do the difference.

Or, you could also subtract:

let opens = "08:00";
let date1 = moment(new Date('1945.10.20 17:30'));
let date2 = moment(new Date('1970.01.08 12:00'));

function timeDifference(opens, end) {
  // get the start
  var start = moment(opens, "HH:mm");
  
  // find how many minutes from midnight the start is
  var startFromMidnight = start.diff(start.clone().startOf("day"), "minutes");
  
  // find how many minutes from midnight the end is
  var endFromMidnight = end.diff(end.clone().startOf("day"), "minutes");
  
  // subtract the two to find the difference
  return endFromMidnight - startFromMidnight;
}

console.log(timeDifference("08:00", date1));
console.log(timeDifference("08:00", date2));
<script src="http://momentjs.com/downloads/moment.js"></script>

Upvotes: 0

chungtinhlakho
chungtinhlakho

Reputation: 930

If I am reading this correctly, you want to compare the hours on your date object to 8AM.

Javascript has getHours() and getMinutes() from date object.

Hence you can do date.getHours() - 8, and date1.getMinutes()

Upvotes: 0

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