I tried looking for an answer but could not find a particular answer which does with Timezone offset. Hence, posting the same really sorry if there are any answer present already.
I have a requirement in the project where I need to convert the time to UTC or GMT based on the time specified by the user and timezone offset value provided by the user. Basically, the user provides his local time and timezone offset value according to his local time. I need to convert that into UTC/GMT time.
I am using the Node.js and following is the data which is available in the Node.js Backend:
Time: 2020-11-05T15:00:00.000Z
Timezone offset value: +02:00
As the timezone offset value is +02:00 I need to subtract it from the time to convert it into the UTC format. so I can get the time as: 2020-11-05T13:00:00.000Z. I using the moment-js as well. Can someone please help me how can achieve this using the Node.js or using the Moment.js?
If the offset takes daylight saving time into account you should be able to do:
const the_date = '2020-11-05T15:00:00.000';
const offset = 2;
const utc_time = moment.utc(the_date).subtract(offset, 'hours');
It's not clear which way you are trying to convert. If you are converting from UTC to a fixed offset, you can use the utcOffset function, like this:
const m = moment.utc('2020-11-05T15:00:00.000Z').utcOffset('+02:00');
m.format(); //=> "2020-11-05T17:00:00+02:00"
Or - if you were trying to convert from +02:00, then you would include that offset in the input instead of the Z (Z means UTC). You would then just call the utc function, like this:
const m = moment('2020-11-05T15:00:00.000+02:00').utc();
m.format(); //=> "2020-11-05T13:00:00Z"
However you should be aware that an offset is not the same as a time zone. A time zone can have more than one offset, one of which will apply at a given point in time. Those offsets can change due to daylight saving time and for changes in standard time. Thus, asking a user to pick "his timezone offset value according to his local time" is problematic - as you may be applying that offset to the wrong point in time. See "Time Zone != Offset" in the timezone tag wiki for further details.
You should also understand Moment's project status, and possibly choose a different library.
After some more research and trying, I was able to convert it. Posting the answer in addition to Christians response (https://stackoverflow.com/a/64701083/7584240) so if anyone is looking for the answer they will have another option:
var moment = require('moment');
var time = "2020-11-05T15:00:00.000Z";
var timeoffset = "+02:00";
time = moment.utc(time).local().format('YYYY-MM-DDTHH:mm:SS.000');
time = moment(time, 'YYYY-MM-DDTHH:mm:ss.000').subtract(timeoffset).format('YYYY-MM-DDTHH:mm:ss.000') + 'Z';
Related
I've got a form where I input an event that starts at a certain time. Let's say 9am.
To assign a date/time object I'm using MomentJs. The issue comes when displaying it in different time-zones.
In London will show up 9am as intended - in Kiev will show 11am.
How can I make MomentJS and the browser ignore which timezone is relevant for the user, and just displaying the time I'm giving?
Here's my code:
<p>
Start time:
{moment(event.startDate).format("HH:mm")}
</p>
Assuming you have stored the date as utc (which in this case you probably should have), you could use the following:
moment.utc(event.startDate).format("HH:mm")
Let me provide an alternative answer in Vanilla JavaScript. If you want to make it timezone 'neutral', you can first convert it to UTC using toISOString().
const current = new Date();
const utcCurrent = current.toISOString();
console.log(utcCurrent);
If you want to convert it to a specific timezone, such as London, you can use toLocaleString(). Do take note of the browser support for the timezone though.
const londonTime = new Date().toLocaleString('en-US', { timeZone: 'Europe/London' })
console.log(londonTime);
What you want is a normalized Datetime. This can get a little confusing since the concept of timezones is a rather arbitrary construct.
I like to think of Datetime values as "absolute" and "relative". An "absolute" Datetime is one that is true regardless of which timezone you're in. The most common example of these are UTC(+000) and UNIX Time (also known as Unix epoch, POSIX Time or Unix Timestampe).
UTC is pretty obvious. Its the current time at +000 timezone. UNIX time is a bit more interesting. It represents the number of seconds that have elapsed since January 1, 1970.
You should always store data, in both client and backend, as an "absolute" time. My preference is UNIX time since its represented as a single integer (nice and clean).
moment.js does this for you. When you instantiate your moment object, you can use:
var date = moment.utc(utcString)
or for Unix Time
var date = moment.unix(unixInt)
You can then use this object to display the date in any form you wish:
console.log(date.tz.("America/Toronto"))
The only way I could solve this is by removing the timezone and milliseconds info from the string. I used date-fns lib but I imagine moment will work the same way.
import { format } from 'date-fns'
const myDateTimeString = '2022-02-22T19:55:00.000+01:00'
const dateTimeWithoutTimezone = myDateTimeString.slice(0, 16) // <- 2022-02-22T19:55
format(new Date(dateTimeWithoutTimezone), 'HH:mm')
I'm attempting to display a duration ticker for something. The start time is always in London time. It works perfectly for people in England/the same timezone, however when people in other time zones look at the duration it displays the wrong value (If you're in a timezone behind England => negative values/too small values, timezone ahead => value too large).
My solution to this was to use moment-timezone. I added the moment timezone data correctly I've attempted to use this timezone data (code simplified and separated into individual lines for easier readability):
let londonTimeNow = moment().tz('Europe/London'),
jobStartTime = moment(job.start, 'DD/MM/YYYY HH:mm:ss'),
diff = londonTimeNow.diff(jobStartTime);
duration = moment.duration(diff).format('HH:mm:ss', {trim: false});
I was hoping this would then get the current time in London and compare to the start time no matter where you are in the world. However, it seems the diff function converts the time to the user's computer time. I tried formatting the londonTimeNow to be a string, but then the diff function doesn't work.
Note, I've debugged and moment().tz() is working correctly, I've tried with other time zones and it gets the correct time in the zone specified.
Any ideas?
EDIT:
It seems I can get it working by manually setting the offset property of 'londonTimeNow' to 0. However this doesn't feel quite right to me. I'd prefer a solution that seems less like a hack.
You should specify the jobstart time in the same way you declare london time using the same timezone:
jobStartTime = moment.tz(jobStart, 'DD/MM/YYYY HH:mm:ss','Europe/London'),
This will set the job start time using the same timezone.
Could you add expected output or specify what you mean by 'diff converts the time'?
The result of diff is a duration and is not in any timezone.
Other than that, the problem seems to be in not using timezone for task start.
Try this:
let londonTimeNow = moment().tz('Europe/London'),
jobStartTime = moment(job.start, 'DD/MM/YYYY HH:mm:ss').tz('Europe/London'),
diff = londonTimeNow.diff(jobStartTime);
duration = moment.duration(diff).format('HH:mm:ss', {trim: false});
Hi im using moment js to convert this string 20:00 I tried:
var a = moment("20:00", "HH:mm")
console.log(a.format()) // 2016-09-08T20:00:00+01:00
the problem when I store in mongodb it become
2016-09-10T19:00:00.000Z
I want to store 2016-09-10T20:00:00.000Z
anyway can explain why please ?
When you say that you want to store 2016-09-10T20:00:00.000Z what you are saying is that you want to assume that your date and time is UTC.
To assume that the date you are parsing is a UTC value, use moment.utc
var a = moment.utc("20:00", "HH:mm")
console.log(a.format()) // 2016-09-08T20:00:00Z
Note that when you parse a time without a date, moment assumes the current date. This may not be the behavior that you want.
I'm also not sure if you want a UTC date (which is what you are saying), or a local date without an offset indicator. If you want a local date without an offset indicator, simply use a format without an offset:
moment.utc("20:00", "HH:mm").format('YYYY-MM-DDTHH:mm:ss.SSS')
"2016-09-08T20:00:00.000"
If you are dealing with local dates that do not have a time zone association, I recommend using moment.utc to parse, as this will ensure that the time does not get shifted to account for DST in the current time zone.
For more information about how to parse dates into the time zone or offset that you would like in moment, see my blog post on the subject.
This it how it should look:
var a = moment("20:00", "HH:mm")
console.log(a.utcOffset('+0000').format())
<script src="http://momentjs.com/downloads/moment.min.js"></script>
Doe, the problem is that you are using timezones when you create the date.
MomentJS uses your current timezone automatically.
Mongo however saves the time as it would be in another timezone.
Therefore, if you want the two strings to format the same way, you need to set the timezone.
Using moment.js, I'm attempting to extract the offset from an ISO date string so I can use the offset later when formatting an epoch timestamp to ensure the conversion of the timestamp is in the same timezone.
Even though the offset in the string is -0400, the result is always 0;
var currentTime = "2015-03-18T16:10:00.001-0400";
var utcOffset = moment(currentTime).utcOffset(); // 0
I've attempted to use parseZone() as well without success. Is there a way to extract -0400 from the string so I can use it while formatting another time?
Thanks for the help!
KC
The correct way to extract the offset is indeed with parseZone
var currentTime = "2015-03-18T16:10:00.001-0400";
var utcOffset = moment.parseZone(currentTime).utcOffset();
This should result in -240, which means 240 minutes behind UTC, which is the same as the -0400 in the input string. If you wanted the string form, instead of utcOffset() you could use .format('Z') for "-04:00" or .format('ZZ') for "-0400".
The form you gave in the question just uses the computer's local time zone. So it is currently UTC+00:00 in your time zone (or wherever the code is running), that would explain why you would get a zero. You have to use parseZone to retain the offset of the input string.
Also - your use case is a bit worrying. Remember, an offset is not the same thing as a time zone. A time zone can change its offset at different points in time. Many time zones do this to accommodate daylight saving time. If you pick an offset off of one timestamp and apply it to another, you don't have any guarantees that the offset is correct for the new timestamp.
As an example, consider the US Eastern time zone, which just changed from UTC-05:00 to UTC-04:00 when daylight saving time took effect on March 8th, 2015. If you took a value like the one you provided, and applied it to a date of March 1st, you would be placing it into the Atlantic time zone instead of the Eastern time zone.
Sorry if the title is a little convoluted. I'm bashing my head against the floor with times in NodeJS / Javascript. I can get the current UTC time like this:
var currentTime = Date.now();
I can get the current time for a user who is, for example, in the -3 timezone like this:
var offsetTime = Date.now() + (numTimeZone * 3600000);
But how do I get the local user time at, say, 6am, converted to UTC?
Practical application:
What I'm trying to do is create an auto-emailer which sends an email to a user at 6am in their local time. My server is in one timezone and they will be in another, so I'm trying to standardise it against UTC so every minute I can set my server to check the currentUTC time, then check what the user's 6am time is converted to UTC (local6am), and if the currentUTC > local6am then an email should be sent.
What's the best way to achieve this? Preferably without using a library if possible.
Utc to Local
moment.utc('2014-02-19 05:24:32 AM').toDate();
Local to utc
Read this documentation.
MomentJS is parsing the date as a locale date-time. If no hour is given, it is assuming midnight.
Then, you convert it to UTC, so it is shifted, according to your local time, forward or backwards. If your are in UTC+N, then you will get the previous date.
moment(new Date('02-19-2014')).utc().format("YYYY-MM-DD HH:mm").toString()
moment(new Date('02-19-2014 12:00')).utc().format("YYYY-MM-DD HH:mm").toString()
(or)
You can try this:
moment.utc('07-18-2013', 'MM-DD-YYYY')
moment.utc('07-18-2013', 'MM-DD-YYYY').format('YYYY-MM-DD')
You do not need to call toString explicitly.