CODEWITHSUNDEEP
javascriptnode.jsdatetypesmomentjs
TechChain
TechChain

Reputation: 8952

Changing Date time zone in Javascript?

I have a date in UTC format `2020-06-19T03:55:12.000Z. Now i am converting into date of US timezone as 

let syncDate = moment(date, 'YYYY-MM-DD[T]HH:mm:ss.SSS[Z]')
    .subtract(7, 'hours')
    .format('YYYY-MM-DD[T]HH:mm:ss.SSS[Z]');

This gives me a date 7 hours behind which is date of US. But i want a date in below format 

2020-06-18T21:00:24.523-07:00

Here if we can see the hours are defined as -7 so please guide how can we achieve the same ?

Upvotes: 2

Views: 1486

Answers (4)

Orilious
Orilious

Reputation: 329

You can't extract a timezone out of your date because there is no timezone information in it. You said "I am converting into a date of US timezone as" But you didn't. You just reduced it for 7 hours. The timezone is still UTC.

You should use moment-timezone (not handling things the hard way and manually as @GetSet said). Here the solution:

const moment = require('moment'); 
const tz = require('moment-timezone');

let date = moment('2020-06-19T03:55:12.000Z');
let syncDate = date.tz('America/Los_Angeles')
console.log(syncDate.format());

But, I suggest you use Day.js. The code will be:

const dayjs = require('dayjs');
const utc = require('dayjs/plugin/utc');
dayjs.extend(utc);

const dDate = dayjs('2020-06-19T03:55:12.000Z');

console.log(dDate.utcOffset(-7*60).format()); //2020-06-18T20:55:12-07:00

I used moment.js in the past. I tried Date-fnd for 24 hours. And finally, I moved to Day.js. It's new (start in late 2018) but it's growing so quick (take a look at this link and put the duration on 5 years). The great thing about it is that "IT ALWAYS DOES WHAT IT SAYS". Moment and Date-fns don't. (not always). It uses a wrapper and so you never work with the Date object directly. It solves difficulties and problems. It's immutable and always returns a new object and you can chain functions. Day.js has the smallest size (2kB).The documentation is awesome and you can up and running very fast. (It's more understandable that the way other libraries work.)

Here I have to say that Dayjs performance is not is good as Moment in calculations but is way better (than especially moment) in parsing and formating.

I strongly suggest you read this article: Why you shouldn't use Moment.js

Edit(1): As @GetSet mentioned in comments for OP that may need a solution in Moment.js I added it to the answer.

Edit(2): Adding the reason why you can't achieve your result the way OP solving it.

Upvotes: 2

Terry Lennox
Terry Lennox

Reputation: 30725

There are a couple of things it is vitally important to point out here.

  1. There is no one US timezone, there are quite a few, for example America/Los_Angeles, America/Denver, America/Chicago, America/New_York, see the IANA Timezone list for all of them.

  2. Please don't convert from one timezone to another using a fixed offset, this is really fragile. You wouldn't believe how many bugs I've seen in my career (from others, and yes, from myself!) due to this one mistake. Many timezones use Daylight Saving Time, so the UTC offset of the timezone varies by the date. For example, the Pacific Timezone currently varies between UTC-08:00 and UTC-07:00.

I would suggest using Moment Timezone to convert from one timezone to another.

For example: 

const dateString = `2020-06-19T03:55:12.000Z`;
const timezones = ["America/New_York", "America/Chicago", "America/Denver", "America/Los_Angeles"];

console.log(`Time in UTC:`, moment(dateString).toISOString());

// Show the time in each timezone
timezones.forEach(timezone => { 
    let timeLocal = moment.tz(dateString, timezone);
    console.log(`Time in ${timezone}:`, timeLocal.format('YYYY-MM-DD[T]HH:mm:ss.SSSZ'))
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script> 
<script src="https://momentjs.com/downloads/moment-timezone-with-data.js">
</script>

Upvotes: 0

Andriy Petrusha
Andriy Petrusha

Reputation: 129

  1. new Date() depends on local computer date setup - if any user has wrong date on his local computer - your system will take wrong dates from those users.
  2. If you working with dates on background (storing in database or any other manipulations) - generate it on background (php, java etc.) and than send it to you html/javascript files.

Upvotes: 1

Mohammad Mostafa Dastjerdi
Mohammad Mostafa Dastjerdi

Reputation: 714

you can use Date().toLocalString() method

// example:
var d = new Date().toLocalString("en-US", {
    month: "long",
    day: "2-digit",
    year: "numeric",
});

for more information see:

https://www.w3schools.com/jsref/jsref_tolocalestring.asp

Upvotes: 0

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