Can anyone help me in converting the below date format into the preferred format?
"Tue Dec 08 18:00:00 IST 2020"
preferred format:
2020-12-08 18:00:00 +05:30
This is not possible because time zone abbreviations are not well defined, and many are not unique.
For example, there are 3 different interpretations of IST:
India Standard Time (UTC+05:30)
Israel Standard Time (UTC+02:00)
Irish Standard Time (UTC+01:00)
You seem to be asking about the first one, but there's no way for a computer to know that when you are considering all of the time zones of the world.
The list of possibilities gets a bit crazy if you start thinking about other details, such as:
Some time zones have more than one abbreviation commonly used.
There are "invented" abbreviations that some people use and others do not.
Many time zones don't have any real abbreviation at all and just use a numeric offset.
There are abbreviations from other languages than just English.
In some languages, your string including the abbreviation might contain non-Latin characters, such as with Asian languages, Cyrillic languages, Hebrew, etc.
Thus, you cannot just convert whatever abbreviation might be in your string to the correct offset. Instead, you need to generate the string such that it already has the offset in it, or you need additional information - such as a time zone identifier (e.g.: "Asia/Kolkata"), or at least a country code and language to help disambiguate the abbreviation.
Related
Take the date '2022-04-01' and another date '2022-05-15' for example. When I calculated their deviation in Chrome devtools, what I got is:
The result is 3801600000. But when my friend did the same thing in another device, what he got is:
The result is 3798000000. The difference between 3801600000 and 3798000000 is exactly one hour. What may causes this result? How can I eliminate this difference?
You lack the zone data:
UTC datetime: new Date("2021-01-01T12:00:00Z");
UTC-4 datetime: new Date("2021-01-01T12:00:00-04:00");
The main issue you are experiencing is because your input string is being interpreted as assigned to the local time zone, and you have different time zones on the two machines you've been testing with. One of them has a DST transition between the two dates, and the other does not - which explains your one hour difference.
The examples you show also reveal your possible time zones:
Your machine is showing 8 hours ahead of UTC (UTC+8) for both timestamps. There are several parts of the world that use UTC+8 without DST, including China, Western Australia, Irkutsk Russia, and many others. There are no places on earth that use UTC+8 in conjunction with DST.
Your friend's machine is a different story. The timestamps are showing 2 hours ahead of UTC (UTC+2) on 2022-04-01, and 3 hours ahead of UTC (UTC+3) on 2022-05-15. While many countries use those offsets (such as those that are in Eastern Europe that use EET/EEST), none of those areas have a DST transition between those two dates. See the bottom of this table of DST transitions. All of the +2/+3 areas of the world transitioned in March. I can only conclude that your friend's machine has some non-standard time zone setting, or they are significantly behind on time zone data updates, or both. (Please reply in comments if I am incorrect on this!)
Also, your input string format, 2022-04-01 00:00:00 is not in the standard date time string format defined by the ECMAScript specification. Thus, it is not guaranteed to be parsed consistently by all browsers. Current versions of Chrome, Edge, and Firefox will interpret it as a local date and time, but the current version of Safari will fail with "Invalid Date".
If you want it interpreted as local time correctly in all browsers, you would need to specify it as 2044-04-01T00:00:00.
If you want it interpreted as UTC then specify as 2044-04-01T00:00:00Z.
If you want it interpreted with a specific time zone offset, then append that instead, as in: 2044-04-01T00:00:00+08:00.
If you must parse the string in the original format, then don't do it using the Date object. Either use a library (such as Luxon or date-fns), or parse it yourself with regex and/or string manipulation techniques.
My client is in india and server in USA . If user submit his post from india it get stored in USA server so when i display post submit time to user it is as per USA time . I want to show it as per clients timezone
The simplest way to handle timezones is to work with Epoch time behind the scenes, and translate it to the user's preferred timezone on render (or with client-side code).
Epoch time is the number of seconds since it became 1 January 1970 in London. For example, right now the time is 1483130714. This means we've got one simple number, that can be effortlessly compared and sorted, to represent precise moments without needing to care about dates, timezones, locales and their frustrating details. Virtually all languages in popular use have the ability to parse these numbers into their own timestamp values. In JavaScript, you can do this with new Date(1483130714). You'll get a date object and you can then present that however you like (eg with toLocaleString).
If you don't use Epoch time, you'd want to use UTC, the next-best thing. The important thing is to store in a consistent universally-understood format and then translate it to the user's preferred form as needed.
You need to store date in UTC and then convert it as per browser culture and timezone. So store all dates in UTC and depending on browser culture you can add offset, this could be tricky if user sets wrong culture and time.
Im struggling with date issues and would love to get some help.
i want to get to offset from UTC by the timezone name.
I am getting my date from the server in this format:
"July 11, 2016::11:09:43 AM IDT" (Time Zone in this case is IDT- but can be any other timezone).
I want to be able to get the offset from IDT (in this case) to UTC.
Is there any way to figure it out?
thanks!
livnat:)
If you examine a list of time zone abbreviations and their corresponding offsets, such as the list on Wikipedia or the list on timeanddate.com, you may be able to find that IDT is an abbreviation for Israel Daylight Time, and is equal to UTC+3. However, upon further examination you'll also find that there are many abbreviations that are ambiguous. For example:
CST could be any of:
Central Standard Time (UTC-6)
China Standard Time (UTC+8)
Cuba Standard Time (UTC-5)
BST could be any of:
British Summer Time (UTC+1)
Bangladesh Standard Time (UTC+6)
Bougainville Standard Time (UTC+11)
... and many others.
You'll also find that two lists I mentioned are not identical. That's because in general, time zone abbreviations are a convention, not a standard.
Therefore, if all you have is an abbreviation, and you want to cover all the time zones of the world, then you cannot uniquely identify the time zone.
That said, if you can limit your list to a set of predefined, non-conflicting abbreviations, then you could certainly work out a mapping table on your own. Alternatively, if you have additional information such as the country, then you can also use that information to disambiguate.
I am working on a very small JavaScript library that allows users to retrieve content based on date. For this content, the date is just an identifier and timezones are completely irrelevant (think along the lines of a Dilbert flip calendar). The "May 14th" content is the same whether you are in the United States or Australia.
The function for retrieving data currently takes a Date object as a parameter. Within the function, the timezone is ignored. Does this approach make sense, or would it be better to take a timezone-independent identifier (like 2012-01-01) as a parameter instead? With the Date object approach, do I run the risk of returning the wrong data as a result of timezone adjustments browsers make?
How about using Date.getUTC*() functions? UTC time is the same for everyone.
After doing some research, it appears that simply ignoring the timezone information is the best approach. Why? This will always preserve the date and time that were provided to the Date constructor (which is my goal), whereas the getUTC* methods will return altered versions of the date and time. For example, take a look at this node REPL session I ran on a computer in the Eastern Time zone.
> d = new Date(2013, 03, 27, 23, 00, 00)
Sat Apr 27 2013 23:00:00 GMT-0400 (EDT)
> d.getDate() // The same date provided in the constructor. Woo!
27
> d.getUTCDate() // A different date. Boo!
28
Long story short, if you want to read the exact date and time that were provided in the Date constructor, using the normal get* methods (like getDate) will do that. If you use the getUTC* methods (like getUTCDate) modified versions of the date and time will be returned.
I know this may sound rudimentary to some of the more experienced programmers out there, but this really helped me make sense of things. I hope it helps others who come along.
The only problem with the approach in your own answer is that it doesn't account for ambiguous times. This happens during daylight savings fall-back transitions.
For example, set your computer's time zone to US Mountain Time ("Mountain Time (US & Canada)" on windows, or "America/Denver" on mac/linux). Then restart your browser and run the following javascript:
var dt = new Date(2013,10,3,1,0);
alert(dt);
This is November 3rd, 2013 at 1:00 AM. But you don't know which 1:00 AM it is representing. Is it in Mountain Daylight Time (UTC-6) before the transition, or Mountain Standard Time (UTC-7) after? There's no way to tell, and JavaScript will just use the standard time.
Now if all you need is 2013-11-03 01:00 - then you are correct. You can just ignore the offset and be done with it. But if you are going to use that value for anything meaningful - such as recording a point in time, or subtracting from another point in time for duration between them, then you have a problem that you can't resolve without the offset.
Unfortunately, there is no great solution for this problem in JavaScript. The closest thing is Moment.js, but it is still not perfect yet. Still, it is better than the Date object by itself, because it gets around browser inconsistencies and provides better parsing and formatting.
What does it mean when you get or create a date in UTC format in JavaScript?
A date represents a specific point in time. This point in time will be called differently in different places. As I write this, it's 00:27 on Tuesday in Germany, 23:27 on Monday in the UK and 18:27 on Monday in New York.
To take an example method: getDay returns the day of the week in the local timezone. Right now, for a user in Germany, it would return 2. For a user in the UK or US, it would return 1. In an hour's time, it will return 2 for the user in the UK (because it will then be 00:27 on Tuesday there).
The ..UTC.. methods deal with the representation of the time in UTC (also known as GMT). In winter, this is the same timezone as the UK, in summer it's an hour behind the time in the UK.
It's summer as I write this. getUTCDay will return 1 (Monday), getUTCHours will return 22, getUTCMinutes will return 27. So it's 22:27 on Monday in the UTC timezone. Whereas the plain get... functions will return different values depending on where the user is, the getUTC.. functions will return those same values no matter where the user is.
getUTC is for converting times to Coordinated Universal Time (UTC, the acronym is ordered differently than what it stands for) which is the standard time based on the time in Greenwich, London.
The universal time is calculated using a time offset (in minutes when in JavaScript.) This offset is based on the time zone configured on the client browser's operating system.
If you plan on storing dates for users in multiple time zones, this is what you should use.
Further to Dan's remark about the acronym being different to what it stands for is a good reason: UTC Abbreviation on Wikipedia