JS date format gives -1 day

Question

I want to format my date with toIsoString function but the function returns -1 day how to fix it? the event.value format is Tue Apr 19 2022 00:00:00 GMT+0400 (Armenia Standard Time)

 console.log(new Date(event.value).toISOString().slice(0,10))

in the console, I'm getting this one 2022-04-18 how you can see the result was -1 day

  startDateChange(event: any): void{
    this.firstDayOfMonth = event;
    console.log(new Date(event.value).toISOString().slice(0, 10));
  }

user_1691311 · Answer

This is because of your timezone settings. The toISOString is always returning +0000 while you work with +0400 in your timezone. This essentially withdraws 4 hours resulting in the day before, 20:00 hours.

You could try to fix this by setting the timezone offset to 0 by adding a Z to the date as shown in the second example.

The third example is a safe way to do it but you need to prefix the 0 if you need that.

Another alternative would be to use a date-library like Moment.js, although moment is deprecated (I don't know for sure what the best alternative would be, that's up to you).

// Your example (this might work for some people that are in the +0000 timezone)
console.log(new Date('2021-03-03T00:00:00').toISOString().slice(0,10));

// Second example
console.log(new Date('2021-03-03T00:00:00z').toISOString().slice(0,10));

// Third example
const date = new Date('2021-03-03T00:00:00');
const year = date.getFullYear();
const month = date.getMonth() + 1;
const day = date.getDate();

console.log(`${year}-${month}-${day}`);

user_1932552 · Answer

You can use https://day.js.org/

Code:

const dateString = 'Tue Apr 19 2022 00:00:00 GMT+0400 (Armenia Standard Time)'

const date1 = dayjs(dateString).format('YYYY-MM-DD')
console.log(date1)

const date2 = dayjs(dateString).format('YYYY-M-D')
console.log(date2)

JS date format gives -1 day

2 Answers