Moment is not adding day

Question

I have the following javascript:

const to = moment(item.to);
const toNextDay = to.add(1, 'days');

item.to is a string that has the following format:

"2020-06-30T00:00:00"

But is not adding the next day, that would be "2020-07-01T00:00:00"

This is the Function:

  private getCurrentRecord(records: ConfigRecord[]) {
    let result: string = null;
    for (let index = records.length - 1; index >= 0; index--) {
      const item = records[index];

      if (item.from && item.to) {

        const from = moment(item.from);
        const to = moment(item.to).add(1, 'days');
        const today = moment();
        console.log(today.format());
        if (from <= today && today < to) {
          result = item.value;
          break;
        }
      }
    }
    return result;
  }

Can you add to a constant? I'm not sure of this rule in javascript, but I'd try making it non-constant. If this works, please notify me, and I'll 'promote' this comment to an answer. — JosephDoggie, Jun 04 '20 at 15:20
See also https://stackoverflow.com/questions/563406/add-days-to-javascript-date -- I'd just make the entity a 'var' not a constant … see my comment above — JosephDoggie, Jun 04 '20 at 15:23
Hello, I tried using 'let' but tslint from Angular is saying that the value is never reassigned, which is true. Also I tried using var but tslint is telling me this: "Forbidden 'var' keyword, use 'let' or 'const' instead (no-var-keyword)". Also, is not working with var — user3442470, Jun 04 '20 at 15:26
@JosephDoggie `const` just means that the reference itself is immutable, it doesn't say anything about the mutability of the object it refers to. — Thomas, Jun 04 '20 at 15:31
Consider using moment's [`isSameOrBefore`](https://momentjs.com/docs/#/query/is-same-or-before/) and [`isBefore`](https://momentjs.com/docs/#/query/is-before/) functions rather than `<=` and ` — Heretic Monkey, Jun 04 '20 at 15:44
Please provide a [mre] showing it not working. Also tell us what time zone you're running the code under, as that can affect the formatted output of the date. — Heretic Monkey, Jun 04 '20 at 15:48

Vivek Patel · Answer 1 · 2020-06-04T16:04:37.040

2

Try this one:

const to = moment("2020-06-30T00:00:00");
const toNextDay = moment(to.add(1, 'days').toDate());

As moment is modifying the original moment object, either use toString() or toDate() to get the modified date.

const to = moment("2020-06-30T00:00:00");
const toNextDay = moment(to.add(1, 'days').toDate());
console.log('In local time => ', toNextDay.toString());

const toUTC = moment.utc("2020-06-30T00:00:00");
const toNextDayUTC = moment.utc(toUTC.add(1, 'days').toDate());
console.log('In UTC => ', toNextDayUTC.toString());

<script src="https://momentjs.com/downloads/moment.min.js"></script>

edited Jun 04 '20 at 16:04

answered Jun 04 '20 at 15:37

Vivek Patel

1,018
1
9
15

1

Can't be done, it must be a moment object as Im evaluating if to is bigger than today (which is a moment object too) – user3442470 Jun 04 '20 at 15:40
1

It's returning July the 2nd. – user3442470 Jun 04 '20 at 15:43
1

I think the locale issue is there. I am getting 1st July. – Vivek Patel Jun 04 '20 at 15:47
1

I think you mean a time zone issue. Locale covers language and country... – Heretic Monkey Jun 04 '20 at 15:49
1

Yeah right. Thanks for correcting. It might be time zone issue. – Vivek Patel Jun 04 '20 at 15:49
1

@user3442470 in which timezone you are? – Vivek Patel Jun 04 '20 at 15:53

score 1 · Answer 2 · answered Jun 04 '20 at 15:29

Check the rest of the code because this part is correct

const to = moment("2020-06-30T00:00:00")

//undefined

to.format()

//"2020-06-30T00:00:00+02:00"

const nextDay = to.add(1, "day")

//undefined

nextDay.format()

//"2020-07-01T00:00:00+02:00"

to.format()

//"2020-07-01T00:00:00+02:00"

A little warning, Moment.add() mutates the moment so after to.add(1, "day") to and nextDay are the same date, 2020-07-01. Use to.clone().add(1, "day") if you don't want to lose the original moment

score 1 · Answer 3 · answered Jun 04 '20 at 15:44

1

Try the following. Parse the string using moment's second argument then use add() to add the specified number of days

var input = "2020-06-30T00:00:00";
let addDay = moment(input, "YYYY-MM-DD hh:mm:ss").add(1, "days");
console.log(addDay.format("YYYY-MM-DDTHH:mm:ss"));

<script src="https://momentjs.com/downloads/moment.js"></script>

answered Jun 04 '20 at 15:44

joy08

7,650
5
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It's returning July the 2nd. – user3442470 Jun 04 '20 at 15:50

Moment is not adding day

3 Answers3