CODEWITHSUNDEEP
javascripttimestampmomentjs
Schmidko
Schmidko

Reputation: 810

How to output date/time in moment without timezone shift

I have a timestamp from the backend and I want to display it with momentjs per console.log() without timeshifting and completly indepented from my browsers timezone. I read many posts on stackoverflow but nothing works. All of my outputs have some timezone included.

let timestamp = "2019-11-19T07:05:00+01:00";
console.log(moment(timestamp).toISOString(true));
console.log(moment.utc(timestamp).format());
console.log(moment.utc(timestamp).toISOString(true)); 
console.log(moment.parseZone(timestamp).format());
console.log(moment.parseZone(timestamp).local().format());
console.log(moment.parseZone(timestamp).utc().format());
console.log(moment(timestamp).utcOffset(timestamp).toISOString(true));
console.log(moment.tz(timestamp, 'Europe/Berlin').toISOString(true));
console.log(moment.tz(timestamp, 'Europe/Berlin').format());
console.log(moment.tz(timestamp, 'Europe/Berlin').unix());
console.log(moment.parseZone(timestamp).format('MM/DD/YYYY HH:mm:ss'));
console.log(moment(timestamp).utcOffset("+0100").format('YYYY-MM-DD hh:mm:ss'));

expected output: 2019-11-19T07:05:00Z The Timezone of the timestamp is: Europe/Berlin My Browsers timezone is switched to something different. I don't understand why this simple problem has no easy solution. :)

Upvotes: 2

Views: 1468

Answers (1)

Matt Johnson-Pint
Matt Johnson-Pint

Reputation: 241485

To meet the requirement you described (keeping the local time while changing the offset) you can do the following:

var result = moment.parseZone("2019-11-19T07:05:00+01:00").utcOffset(0, true).format();
console.log(result); //=> "2019-11-19T07:05:00Z"
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.min.js"></script>

Step by step explained:

moment.parseZone("2019-11-19T07:05:00+01:00") // Parses the string, retaining the offset provided
      .utcOffset(0, true)  // sets the offset to zero while keeping the local time
      .format()            // formats the output, using Z to represent UTC

However - You should recognize that these are not the same moments in time. The output timestamp is one hour earlier than the input timestamp. This is explained in the documentation as follows (emphasis mine):

The utcOffset function has an optional second parameter which accepts a boolean value indicating whether to keep the existing time of day.

  • Passing false (the default) will keep the same instant in Universal Time, but the local time will change.

  • Passing true will keep the same local time, but at the expense of choosing a different point in Universal Time.

Thus, it is usually the wrong choice when you already have a specific point in time, either in UTC or as an offset from UTC (like your example input value).

Instead, you should expect that converting from local time to UTC will indeed change the date and time portion of the timestamp. You can use .utcOffset(0, false), or .utcOffset(0), or simply .utc() to do the conversion correctly.

Upvotes: 4

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