I have 2 Dates, One in UTC format and the other one in local time. Now I need to convert the local time to UTC by referring the UTC date time that is there. How to achieve this? Also, I want to make sure the local to UTC conversion handles daylight as well.
Eg: I have an UTC time 2023-02-16T10:00:00Z. and I have a regular time 2023-02-16T16:00:00. Assume the local time is PST, the offset should be -08:00. I understand i can do it in bruteforce way to achieve this. But is there an easy way to do this in JavaScript?
Related
I need to represent date in the format 2021-11-21T00:00:00+00:00 but I get 2021-11-21T00:00:00+05:30. Please help me with this
moment('2021-11-21').format(); //2021-11-21T00:00:00+05:30
I had a similar problem when dealing with dates and birthdays in Golang, but this also applies to Javascript, I'd say. You should not try to use a date object for this task, because you can never fully rely on that when a clients browser is set to a different time zone. I ended up creating a date object myself, consisting only of 3 integers for day, month, year. By doing so you can be sure that time does not play a role at all.
By the way, this might be of interest to others as well: I did some research on how birth dates are handled in general, because when you think about it, your birthday is actually a point in time, so your birthday could change to the previous or the following day, if you look at it from a local perspective. I found out that birthdates (or dates "in general") are not considered as a time or datetime, only the year, month and day are important and they are always the same, regardless of the place/timezone you were born and regardless of the timezone the client lives in.
Instead of using moment, you can use moment-timezone and set it to GMT-0.
var moment = require("moment-timezone");
const time = moment().tz("Etc/GMT").format();
console.log(time);
And the result is something like:
2021-10-26T11:39:15Z
So I think you can't do that (except manually remove the 'Z' and add the +00:00) part as an extra string.
All dates are represented in your system local timezone. This means that moment('2021-11-21') is midnight of November 21st in your timezone (2021-11-21T00:00:00+05:30). If I run the exact same method then it will be local for my timezone (2021-11-21T00:00:00-06:00). If you need this to be in a specific timezone, or in GMT, then you probably want to use moment-timezone and cast the date to that timezone.
moment('2021-11-21').startOf('day').format()
So, I have the 1st day of month as 2019-04-01T00:00:00.000Z
When I use moment(date).month(), it returns me 2, not 3.
So, I receive March, not April.
What is the problem with it, and why I receive the previous month from the date? Maybe the problem in the TimeZone? Because my TimeZone is GMT-4, so, maybe this is problem?
Should I use UTC or ISO string instead to work with the date?
Like you mentioned, your timezone is GMT-4. The date that you are providing is in UTC. The 'Z' at the end stands for Zulu time, which is the same as UTC.
momentjs will convert this to local time.
How to handle this all depends on what you need the date for.
If this is a date that you saved somewhere before on a server, it might be important to add the correct timezone to it when you are saving it.
Be careful if you let a server create these dates, because the server might be running in a different timezone than your client.
If you create a new Date() in JS it will return a date object with the current time of your local time. If this happens on a server that's running in a different timezone, or in UTC (for example Docker containers), it will create a date in that timezone.
The best way to solve this is to think about your exact use case.
There are tons of articles written about handling dates and it's not easy.
If you have some time, this podcast helps to explain how dates work and will help you to get a better understanding of dates in general:
Coding Blocks - Why Date-ing Is Hard
I am getting date time stored as string in New York timezone (GMT -4) format from third-party website. I want to convert it to local time zone using javascript. Date time is saved in following format
"2019-04-15 19:09:16"
I know i can achieve this through MomentJS but I want to know if there is any simple solution beside loading all library to convert date time to local timezone.
On Chrome expected output could be achieved by appending GMT-4 at the end of date and
new Date("2019-04-15 19:09:16 GMT-4")
But this solution doesn't work on Firefox because of invalid format.
If you actually know that the offset is UTC-4, then you simply need to reformat your string to be compliant with the ECMAScript Date Time String Format, which is a simplification of the ISO 8601 Extended Format.
new Date("2019-04-15T19:09:16-04:00")
However, note that New York is on US Eastern Time, which is actually in daylight saving time for the date and time you provided. In other words, it isn't UTC-4 (EST), but rather UTC-5 (EDT). So for that example, it should be:
new Date("2019-04-15T19:09:16-05:00")
But what if you don't know which offset it is for a given time zone on a particular date and time? After all, time zones, daylight saving time transitions, and associated offset are different all over the world, and have changed throughout history. So one cannot just assume a time zone has a single number that is its offset. (Read more under "Time Zone != Offset" in the timezone tag wiki.)
Presently, JavaScript cannot help you with that on its own. Instead, you'll need to use a library, such as the ones referenced here.
For example, using Luxon, you can do the following:
luxon.DateTime.fromISO("2019-04-15T19:09:16", { zone: "America/New_York" }).toJSDate()
In the future, we hope to solve this in the JavaScript language via Temporal objects - which are still in the ECMAScript proposal stage.
I need to get a timezone from a time, date is not important, but daylight savings is.
something like:
timezone = function("15:00");
Is there a simple way to do this?
I dont think you can get the timezone from the time but you might get some help from Date.prototype.getTimezoneOffset()
The getTimezoneOffset() method returns the time-zone offset from UTC,
in minutes, for the current locale.
Example:
var x = new Date();
var currentTimeZoneOffsetInHours = x.getTimezoneOffset() / 60;
No, of course not. Think about it, you're passing 15:00 to that function, presumable denoting it's 3PM. But in what timezone is it 3 PM? No way of knowing. It's like me saying it's quarter to, without saying what hour it's quarter to to.
The only way you can get a timezone in JS is by using the Date object, but that just shows the timezone of the machine on which your code is running, nothing about the TZ that "created" the time you're processing.
Also note that daylight saving isn't a global phenomenon, quite the contrary. AFAIKT, there isn't a single time-zone where DST has always been in place...
In order to get TimeZone information you need more than a Date (and an offset). You need a location.
Javascript does not know the location that it resides in but it does know the current offset from UTC. That is different than a Time Zone. The daylight savings time issue play havoc with this key difference.
This has posed problems when dealing with server applications that know their timezone and report dates as being in a specific Time Zone.
My rule of thumb has been fairly simple in this regard.
Always use Long or long (a 64 bit number) to store, pass and process dates times or intervals, only convert to Date, Calendar or DateTime objects when interacting with people.
Once you have a date object, such as with new Date(), you can use .getTimezoneOffset() to get the number of minutes between the date's object and UTC, which is timezone information you can use.
I've been digging through as many things as I can find, and I can't seem to find what it is I am looking for, so I am coming to the conclusion that I either don't know what I am looking for or its not possible. Either way..
What I am trying to achieve is taking a timestamp example: 1373439600000 and a given offset of -12 to 12 (is that correct, as far as range goes?) so I can then take that timestamp above subtract from it accordingly, and pass that new timestamp to the Date() function so I can then manipulate it for human readable display.
The offset is two part, It is user specified in one instance while in the other it is going to default to the local getTimezoneOffset() if not specified. So trying to figure out how to take that range and work with that. To do everything accordingly.
Ideas? Am I even approaching this in a correct manor?
The timestamps I am working with are already UTC, not sure of that makes a difference.
The JavaScript Date type has many problems, but one of its major quirks is that it only understands two time zones - UTC, or Local. It uses UTC internally and in certain properties and functions like .toUTCString(), but otherwise it uses the local time zone.
Many browsers will accept an offset when parsing a Date from a string, but that will just be used to set the UTC time. Anything on the way out will be converted back to the local time zone again.
Fortunately, there are some great libraries out there for working around these problems. Moment.js is perfectly suited for this. Here is an example of what you might be looking for:
moment(1373439600000).zone(8).format("YYYY-MM-DD HH:mm:ss Z")
// output: "2013-07-09 23:00:00 -08:00"
Of course, you can format as needed, or pass in a more complex zone offset like "+05:30". And if you need to use an actual IANA time zone, there is the moment-timezone companion project, which you could do something like this:
moment(1373439600000).tz('America/New_York').format("YYYY-MM-DD HH:mm:ss Z")
// output: "2013-07-10 03:00:00 -04:00"
Unfortunately the Date object does not provide may facilities for working with timezones. If you have the offset though, you should be able to compute the offset in milliseconds. Then you can add (subtract?) that value to your timestamp and use it to construct the appropriate Date.
Does that help?