I have the following timezones:
when a user selects a timezone from the list how do i get whats the current time and date at that timezone? for example if i choose "Azores" i want to get the current date time for that area.
In moment i could use IANA timezones and pass the timezone like and format it to ("dddd, D MMM YYYY" )
moment().tz().guess;
but the user doesnt want to use IANA Timezones because they cant find some of the countries so i cant go with that option.
Is there a way i can determine the current datetime based on the timezones specified?
i also tried the following if i passed in the offset but that didnt work example:
moment().utcOffset("-01:00");
because its taking my local time and offsetting it so it doesnt give me the actual current datetime.
To get all available timezones:
How to get list of all timezones in javascript
const arr = Intl.supportedValuesOf('timeZone');
JS Date object is in UTC, so to get Date with timezone offset you can use
I want to get New York time in this JavaScript clock?
const date = new Date(new Date().toLocaleString("en-US", {timeZone: "America/New_York"}));
I am processing some itinerary data where the times and dates are all provided in the local timezone. I am adding this data to a database where I'd like to store all of the dates in UTC, with the proper timezone offset. I'm trying to process these dates with moment.js.
The input string for date/time is formatted like this 2020-07-12 13:00 and the timezone is in this format Europe/Amsterdam.
I want to end up with a string like:
2020-07-12T11:00:00+02:00
The trouble I'm having, is that moment converts my input time to either local time or utc if I use the .utc() method.
This code is getting me the correct result, but I don't understand why and I'm not sure if I can rely on its accuracy:
var offset = moment.tz(`Europe/Amsterdam`).utcOffset();
var m = moment(`2020-07-12 13:00`, 'YYYY-MM-DD HH:mm').utc().subtract(240 + offset + offset, 'minutes').utcOffset(offset); // (240 is my own UTC offset)
How can I simply input a date, time and timezone and end up with a correct ISO8601 DateTime?
If you are already using Moment and Moment-TimeZone in your app, then you can simply do the following:
const m = moment.tz('2020-07-12 13:00', 'YYYY-MM-DD HH:mm', 'Europe/Amsterdam');
m.format() //=> "2020-07-12T13:00:00+02:00"
However, the Moment team recommends using Luxon for new development. The equivalent is:
const dt = luxon.DateTime.fromFormat('2020-07-12 13:00', 'yyyy-MM-dd HH:mm', { zone: 'Europe/Amsterdam'});
dt.toISO() //=> "2020-07-12T13:00:00.000+02:00"
The only difference being that milliseconds are included. You can use a different formatting function if you prefer a different output.
The main benefit of Luxon is that it uses the built-in time zone functionality provided by the ECMAScript Internationalization API, whereas Moment-Timezone bundles its own time zone data - which can be quite large.
Also, note that in your question by asking for 2020-07-12T11:00:00+02:00 you seem to be misunderstanding the ISO 8601 format. In that format, the time presented is the local time. Thus, it should be 13:00, not 11:00. The +02:00 means, "this was the offset from UTC for this local time". (It doesn't mean that you apply the offset to get the local time.)
I am working on a cloud based application which deals extensively with date and time values, for users across the world.
Consider a scenario, in JavaScript, where my machine is in India (GMT+05:30), and I have to display a clock running in California's timezone (GMT-08:00).
In this case I have to get a new date object,
let india_date = new Date()
add it's time zone offset value,
let uts_ms = india_date.getTime() + india_date.getTimezoneOffset()
add california's timezone offset value,
let california_ms = utc_ms + getCaliforniaTimezoneOffsetMS()
and finally the date object.
let california_date: Date = new Date(california_ms)
Is there any way to directly deal with these kinds of time zones without having to convert the values again and again?
First, let's talk about the code in your question.
let india_date = new Date()
You have named this variable india_date, but the Date object will only reflect India if the code is run on a computer set to India's time zone. If it is run on a computer with a different time zone, it will reflect that time zone instead. Keep in mind that internally, the Date object only tracks a UTC based timestamp. The local time zone is applied when functions and properties that need local time are called - not when the Date object is created.
add it's timezone offset value
let uts_ms = india_date.getTime() + india_date.getTimezoneOffset()
This approach is incorrect. getTime() already returns a UTC based timestamp. You don't need to add your local offset. (also, the abbreviation is UTC, not UTS.)
Now add california's timezone offset value
let california_ms = utc_ms + getCaliforniaTimezoneOffsetMS()
Again, adding an offset is incorrect. Also, unlike India, California observes daylight saving time, so part of the year the offset will be 480 (UTC-8), and part of the year the offset will be 420 (UTC-7). Any function such as your getCaliforniatimezoneOffsetMS would need to have the timestamp passed in as a parameter to be effective.
and finally the date object
let california_date: Date = new Date(california_ms)
When the Date constructor is passed a numeric timestamp, it must be in terms of UTC. Passing it this california_ms timestamp is actually just picking a different point in time. You can't change the Date object's behavior to get it to use a different time zone just by adding or subtracting an offset. It will still use the local time zone of where it runs, for any function that requires a local time, such as .toString() and others.
There is only one scenario where this sort of adjustment makes sense, which is a technique known as "epoch shifting". The timestamp is adjusted to shift the base epoch away from the normal 1970-01-01T00:00:00Z, thus allowing one to take advantage of the Date object's UTC functions (such as getUTCHours and others). The catch is: once shifted, you can't ever use any of the local time functions on that Date object, or pass it to anything else that expects the Date object to be a normal one. Epoch shifting done right is what powers libraries like Moment.js. Here is another example of epoch shifting done correctly.
But in your example, you are shifting (twice in error) and then using the Date object as if it were normal and not shifted. This can only lead to errors, evident by the time zone shown in toString output, and will arise mathematically near any DST transitions of the local time zone and the intended target time zone. In general, you don't want to take this approach.
Instead, read my answer on How to initialize a JavaScript Date to a particular time zone. Your options are listed there. Thanks.
JavaScript Date objects store date and time in UTC but the toString() method is automatically called when the date is represented as a text value which displays the date and time in the browser's local time zone. So, when you want to convert a datetime to a time zone other than your local time, you are really converting from UTC to that time zone (not from your local time zone to another time zone).
If your use case is limited to specific browsers and you are flexible on formatting (since browsers may differ in how they display date string formats), then you may be able to use toLocaleString(), but browsers like Edge, Android webview, etc do not fully support the locales and options parameters.
Following example sets both the locale and timezone to output the date in a local format that may vary from browser to browser.
const dt = new Date();
const kolkata = dt.toLocaleString('en-IN', { timeZone: 'Asia/Kolkata' });
const la = dt.toLocaleString('en-US', { timeZone: 'America/Los_Angeles' });
console.log('Kolkata:', kolkata);
// example output: Kolkata: 19/3/2019, 7:36:26 pm
console.log('Los Angeles:', la);
// example output: Los Angeles: 3/19/2019, 7:06:26 AM
You could also use Moment.js and Moment Timezone to convert date and time to a time zone other than your local time zone. For example:
const dt = moment();
const kolkata = dt.tz('Asia/Kolkata').format();
const la = dt.tz('America/Los_Angeles').format();
console.log(kolkata);
// example output: 2019-03-19T19:37:11+05:30
console.log(la);
// example output: 2019-03-19T07:07:11-07:00
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment-timezone/0.5.23/moment-timezone-with-data.min.js"></script>
Well, you really do kind of have to convert anytime you want to change the display, but it's not as bad as you think.
First, store all time as UTC. Probably using the milliseconds format, e.g. Date.UTC().
Second, do all manipulation / comparison using that stored info.
Third, if your cloud-based application has an API that API should only talk in terms of UTC as well, though you could provide the ISO string if you prefer that to the MS, or if you expect clients to handle that better.
Fourth and finally, only in the UI should you do the final conversion to the local date/time string, either with the method you're describing or using a library such as momentjs
new Date creates a Date object with a time value that is UTC. If you can guarantee support for the timeZone option of toLocaleString (e.g. corporate environment with a controlled SOE), you can use it to construct a timestamp in any time zone and any format, but it can be a bit tedious. Support on the general web may be lacking. A library would be preferred in that case if you need it to work reliably.
E.g. to get values for California, you can use toLocaleString and "America/Los_Angeles" for the timeZone option:
var d = new Date();
// Use the default implementation format
console.log(d.toLocaleString(undefined, {timeZone:'America/Los_Angeles'}));
// Customised format
var weekday = d.toLocaleString(undefined, {weekday:'long', timeZone:'America/Los_Angeles'});
var day = d.toLocaleString(undefined, {day:'numeric', timeZone:'America/Los_Angeles'});
var month = d.toLocaleString(undefined, {month:'long', timeZone:'America/Los_Angeles'});
var year = d.toLocaleString(undefined, {year:'numeric', timeZone:'America/Los_Angeles'});
var hour = d.toLocaleString(undefined, {hour:'numeric',hour12: false, timeZone:'America/Los_Angeles'});
var minute = d.toLocaleString(undefined, {minute:'2-digit', timeZone:'America/Los_Angeles'});
var ap = hour > 11? 'pm' : 'am';
hour = ('0' + (hour % 12 || 12)).slice(-2);
console.log(`The time in Los Angeles is ${hour}:${minute} ${ap} on ${weekday}, ${day} ${month}, ${year}`);
Getting the timezone name is a little more difficult, it's difficult to get it without other information.
I want to construct a Date object along with dynamically selected timezone. I am currently in IST time zone. I want to eliminate the usage of Date.parse() as it does not behave as expected at times.
let's assume tzOffset to be +05:30 for now. It could be any other timezone based on what users want. new Date(epochDate).toISOString(); converts the date to UTC timezone. How do I get the date in toISOString() format but also get it in the desired time zone
const tsConstruct = `${year}-${month}-${date}T${hour}:${min}:00${tzOffset}`;
const epochDate = Date.parse(tsConstruct);
scheduledTs = new Date(epochDate).toISOString();
JavaScript's Date does not store timezone info. It just stores the number of milliseconds from UNIX EPOCH. Then, depending if you use the UTC methods or not, it returns the date and time in UTC or the local time.
You should have to change the date and time, based on the timezone indicated, to UTC or local time, and then store it in a Date object. But, of course, to show the stored time in another timezone different to the local one or UTC, you must do the conversions yourself, so, as #RuChengChong suggested, use a helper library like momentjs.
Can anyone let me know how to convert a string to a date Object with UTC time zone in ExtJs?
String is "2015-10-07T23:59:00". I would like to get the same in Date Object without changing the timezone.
First of all, your date string does not have a timezone.
When you make a JavaScript date object from a string, there are two possible outcomes you could expect:
You may want the date to be 23:59 Local (23:59 CEST in my case).
In this case, you want to use new Date("2015-10-07 23:59:00") with plain javascript (note the missing T), or Ext.Date.parse("2015-10-07T23:59:00","c");.
You may want the date to be 23:59 UTC (e.g. 01:59 CEST).
In this case, you want to use new Date("2015-10-07T23:59:00").
Of course, whenever you output the date, you have to get the date in the correct time zone as well. The console/toString will usually show it in local time. JavaScript does provide getUTC... methods if you require other time zones.
You see, using Time Zones with JavaScript is a painful experience. I would recommend to try moment.js if you need full time zone support.
You can use Ext.Date.parse.It gives Date Object as output.It syntax is:
Ext.Date.parse( String input, String format, [Boolean strict] )
For Example:
Ext.Date.parse("2015-10-07T23:59:00", "Y-m-dTH:i:s");
try
var millisFromEpoch = Date.parse('2015-10-07T23:59:00');
it will parse date in GMT timezone, Ext.date.parse use the current timezone instead