I am using Javascript code such as that shown below, and recently found that while Date.prototype.toLocaleTimeString() on one machine appends " GMT" or " BST" (depending on the time of year); on another machine, nothing is appended.
var m = new Date();
var time = m.toLocaleTimeString();
I use the returned string to create a log file, and would like the file names to have a canonical structure. I don't mind which of the two string formats is returned, as long as it is the same on both machines.
By the way, I also tried providing first and second arguments, such as m.toLocaleTimeString('en-gb', { hour: '2-digit', minute: '2-digit', second: '2-digit' }), or m.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit', second: '2-digit' }), but then the seconds are no longer included in the returned string.
You could create a custom format function for your logs, using the Date.getHours(), getMinutes() etc.
This should be consistent across platforms and would allow any customization to be added easily.
function formatTimestamp(date) {
const hms = [date.getHours(), date.getMinutes(), date.getSeconds()];
return hms.map(s => (s + '').padStart(2, '0')).join(':');
}
console.log('Timestamp:', formatTimestamp(new Date()));
The behavior you are seeing with the toLocaleTimeString() method is likely due to differences in the default time zone settings on the two machines. The method returns a string that represents the time in the current time zone, which can be different depending on the machine's settings.
You can use toUTCString() method to get a string representation of the date in UTC format, this will always return the same format, regardless of the machine's time zone settings.
var m = new Date();
var time = m.toUTCString();
Another approach, you can use moment.js library, this library will handle timezone and other time related issues, and it's very useful when you are working with dates and time, it will give you a consistent format across different environments.
var moment = require('moment');
var time = moment().format('HH:mm:ss');
The moment().format('HH:mm:ss') will give you the time in the format of HH:mm:ss and you can use this as your log file name.
Additionally, you can also set your machine's time zone to a specific value using the Intl.DateTimeFormat() method, this will help you to get the same format across different machines.
var m = new Date();
var options = {timeZone: 'UTC', hour: '2-digit', minute: '2-digit', second: '2-digit'};
var time = new Intl.DateTimeFormat('en-GB', options).format(m);
This will give you the time formatted to 'en-GB' time zone and with the hour, minute and second digits.
I need to take an hour and convert it to local time as such :
const dataDate = '07:08'
const utcDate = new Date(dataDate);
console.log(utcDate)
there are a few problems with my approach
this only works if i add a date too
this converts to utc
I need to only convert the hour to local time, I also need to parse it to something like this :
[parseInt(hour), 0, 0, 0].map(function (x) { return parseInt(x, 10); })
To give more context, I need to create a shareable calendar with a specific schedule, and the user can set the specific hours for some event to be displayed.
If you have access to the full date
Considering your use-case is that of a shareable calendar, I'm assuming you
have access to the full UTC date. If that's not the case, skip to the next
section.
// The important thing is getting a `Date` object. The timezone in the timestamp
// doesn't really matter at this point. It will be handled internally anyway.
const date = new Date("2011-11-11T07:08:00Z");
Once you have the date object, if all you really want to get is the hour,
you can do so with the methods below. But note that you should probably use the same method for getting not only the hours, but any part of the date or time throughout your application.
const utcHour = date.getUTCHours(); //> 7
// For the hour according to the timezone configured in the RUNTIME
// environment (e.g. the user's browser, if running on the client side):
const runtimeHour = date.getHours(); //> 8 (depends on the runtime timezone)
// For an arbitrary timezone, in case you have the user's timezone stored in
// a config you could use the `.toLocaleTimeString()` method.
// Note that this method is VERY slow (~6000 times slower than `.getHours()`
// for example in a quick benchmark I ran in my machine on Node 16). You
// should probably be careful about how often this is being called (e.g. in
// loops or in a frontend component that is frequently updated/rendered).
const tzHour = Number(date.toLocaleTimeString("en", {
hour: "numeric", // omit minutes and seconds
hour12: false, // force it to be 0-23
timeZone: "America/Sao_Paulo" // set the user's timezone
})); //> 5
Which one you should use really depends on your exact implementation. You might also want to check this answer that further explains how time zones are handled by Date.
NOTE: the .toLocaleTimeString() method depends on the
Intl.DateTimeFormat API. Check Date.prototype.toLocaleTimeString() at MDN
for a compatibility table.
Note about manually calculating time offsets
You need the date in order to reliably adjust the time.
If you don't have the date for some reason, you could do so but that would
mean quite some work and it would never really be reliable, as you would not be
able to factor in Daylight Saving Time adjustments, for example.
Also keep in mind that some timezones operate on fractions of an hour:
+XX30: Asia/Tehran, Asia/Kabul, Australia/Adelaide...
+XX45: Australia/Eucla
Australia/Lord_Howe has a Daylight Saving Time adjustment of 30 mins;
Depending on the requirements of your application, calculating this manually
might not be as simple as you expect. I would recommend to delegate these
calculations to the internal Date implementation (as shown in the previous section) instead of trying to adjust the time manually (keep in mind you would have to handle overflows from min → hour → day → month → year).
About parsing the time string
As for the parsing of the time string, you mentioned in your question, you could do something like:
const rawTime = "07:08";
const [hour, minutes, seconds = 0] = rawTime.split(":").map(Number); //> [7, 8, 0]
// or if you only care about the hours
const hour = Number(rawTime.split(":", 1)); //> 7
// or you could also use a quirk of `parseInt()`, as it ignores everything
// starting at the first non-numeric character:
const hour = parseInt(rawTime); //> 7
If you instantiate a new date with new Date() the retuned value is current date/time in UTC timezone.
You can then set a specific hour/minute to that using Date.setHours() and Date.setMinutes().
Finally you can convert that UTC date to local date via Date.toLocaleDateString()
So I would do something like this for your case:
const date = new Date();
const [hour, minute] = '7:28'.split(':')
const options = {
year: 'numeric',
month: 'long',
day: 'numeric',
hour: 'numeric',
minute: 'numeric',
second: 'numeric',
};
date.setHours(hour);
date.setMinutes(minute);
console.log(date.toLocaleDateString('en-US', options));
I have tried to create a time converter, which converts an upcoming time (for example 2:00pm EDT) to another time zone (for example UTC). The upcoming time is stored in a string at first, and gets converted into a date (I'm not very good at using Dates) (let date = Date.parse(time + ', ' timezone)), but it gives either Invalid Date or NAN.
If someone knows how to convert a string containing the time into another timezone, please share it in the comments.
It's best to use a dedicated Date/Time library, such as luxon for this type of conversion.
We create a DateTime object in the desired timezone, in this case 'America/New_York' (this is more precise that the abbreviation EDT which is ambiguous).
The date can be converted to UTC using DateTime.toUTC();
const{ DateTime } = luxon;
const dt = DateTime.fromObject( { year: 2022, month: 8, day: 5, hour: 14 }, { zone: 'America/New_York'} )
console.log('Time (in zone):', dt.toString());
console.log('Time (UTC): ', dt.toUTC().toString());
.as-console-wrapper { max-height: 100% !important; }
<script src="https://cdnjs.cloudflare.com/ajax/libs/luxon/3.0.1/luxon.min.js" integrity="sha512-6ZJuab/UnRq1muTChgrVxJhSgygmL2GMLVmSJN7pcBEqJ1dWPbqN9CiZ6U3HrcApTIJsLnMgXYBYgtVkJ8fWiw==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
You just have to use .toISOString() method.
new Date(time).toISOString() it will automatically convert to UTC
I have an initial value for a timestamp (created in User-1's timezone) I'm retrieving from firebase's firestore. the format this is in, is seconds in UTC from the Unix Epoch.
My goal is to take the initial timestamp value, and convert it to the timezone of the current user. if I use
moment.unix(initial_In_Seconds).format("H:mma") I get the correct initial time. Using .unix() is the only way I've been able to get the correct initial time. Now I need to convert it to a specific timezone. lets say "America/Denver" (the initial timezone is GMT -05:00)
I haven't been successful using moment.tz() in any of my amalgamations thus far.
I've tried:
moment.tz(moment.unix(initial_In_Seconds).format("H:mma"), "America/Denver")
let unix = moment.unix(initial_In_Seconds).format("H:mma");
let parsed = moment.tz(unix, "America/Denver");
How can this be parsed? Moment.js confuses me
If your timezone offset is specified using IANA representative locations, such as 'America/Denver', then you can likely use toLocaleString provided the locations aren't too obscure (i.e. aren't unsupported by ECMAScript implementations likely to run your code), e.g.
function timeValueWithTimezone(unixOffset, loc) {
let d = new Date(unixOffset * 1000);
return d.toLocaleString(void 0, {
hour12: true,
hour: 'numeric',
minute: '2-digit',
timeZone: loc
});
}
let timeValue = 1582090120;
let loc = 'America/Denver';
console.log('At your local time: ' +
new Date(timeValue * 1000).toLocaleString(void 0, {
hour12: true,
hour: 'numeric',
minute: '2-digit'
}));
console.log('Denver local time is: ' + timeValueWithTimezone(timeValue, loc));
further playing has yielded better results:
moment
.tz(moment.unix(props.navigation.state.params.time.start.seconds),'America/Denver')
.format('H:mma')
unfortunately for hours that are PM, it gives military time...and im interested in 12hr format...
EDIT: changes -> .format('h:mma') yields 12hr format
I need a way to detect the timezone of a given date object. I do NOT want the offset, nor do I want the full timezone name. I need to get the timezone abbreviation.
For example, GMT, UTC, PST, MST, CST, EST, etc...
Is this possible? The closest I've gotten is parsing the result of date.toString(), but even that won't give me an abbreviation. It gives me the timezone's long name.
A native solution:
var zone = new Date().toLocaleTimeString('en-us',{timeZoneName:'short'}).split(' ')[2]
console.log(zone)
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleDateString
You can pass undefined instead of en-us to default to the browser's current locale.
moment-timezone includes an undocumented method .zoneAbbr() which returns the time zone abbreviation. This also requires a set of rules which are available to select and download as needed.
Doing this:
<script src="moment.js"></script>
<script src="moment-timezone.js"></script>
<script src="moment-timezone-data.js"></script>
<script>
moment().tz("America/Los_Angeles").zoneAbbr();
</script>
Returns:
'PDT' // As of this posting.
Edit (Feb 2018)
Evan Czaplicki has worked on a draft proposal to add a time zone API to browsers.
The Date object doesn't have a method for getting the timezone abbreviation, but it is implicit at the end of the result of toString. For example,
var rightNow = new Date();
alert(rightNow);
...will return something like Wed Mar 30 2011 17:29:16 GMT-0300 (ART). The timezone abbreviation can be isolated between parentheses:
var rightNow = new Date();
alert(String(String(rightNow).split("(")[1]).split(")")[0]);
The output will be the timezone abbreviation, like ART.
This works perfectly in Chrome, Firefox but only mostly in IE11. In IE11, timezones without straight forward abbreviations like "Indian Chagos Time" will return "ICT" instead of the proper "IOT"
var result = "unknown";
try{
// Chrome, Firefox
result = /.*\s(.+)/.exec((new Date()).toLocaleDateString(navigator.language, { timeZoneName:'short' }))[1];
}catch(e){
// IE, some loss in accuracy due to guessing at the abbreviation
// Note: This regex adds a grouping around the open paren as a
// workaround for an IE regex parser bug
result = (new Date()).toTimeString().match(new RegExp("[A-Z](?!.*[\(])","g")).join('');
}
console.log(result);
Result:
"CDT"
You can use the formatToParts method of Intl.DateTimeFormat to get the short time zone abbreviation. In certain parts of the world this may return strings like "GMT+8", rather than the abbreviation of an actual time zone name.
let timeZone = new Intl.DateTimeFormat('en-us', { timeZoneName: 'short' })
.formatToParts(new Date())
.find(part => part.type == "timeZoneName")
.value
console.log(timeZone)
Update for 2021
moment.js is now deprecated and they suggest using Luxon in new projects instead.
You can get a timezone abbreviation with Luxon like:
import { DateTime } from 'luxon'
DateTime.local().toFormat('ZZZZ') // => for ex: "PDT"
Note: The output format depends on the set locale. For more information see this answer.
I was able to achieve this with only moment.
moment.tz(moment.tz.guess()).zoneAbbr() //IST
Using contents from new Date().toString()
const timeZoneAbbreviated = () => {
const { 1: tz } = new Date().toString().match(/\((.+)\)/);
// In Chrome browser, new Date().toString() is
// "Thu Aug 06 2020 16:21:38 GMT+0530 (India Standard Time)"
// In Safari browser, new Date().toString() is
// "Thu Aug 06 2020 16:24:03 GMT+0530 (IST)"
if (tz.includes(" ")) {
return tz
.split(" ")
.map(([first]) => first)
.join("");
} else {
return tz;
}
};
console.log("Time Zone:", timeZoneAbbreviated());
// IST
// PDT
// CEST
You can use the Native Javascript date object.
Just hardcode the long timezone name 'America/Los_Angeles.
var usertimezone = 'America/Los_Angeles';
var usertimezoneabbreviation = new Date().toLocaleTimeString('en-us',{timeZone: usertimezone, timeZoneName:'short'}).split(' ')[2];
console.log(usertimezoneabbreviation); //PDT
If all else fails, you can simply create your own hashtable with the long names and abbreviations.
Updated for 2015:
jsTimezoneDetect can be used together with moment-timezone to get the timezone abbreviation client side:
moment.tz(new Date(), jstz.determine().name()).format('z'); //"UTC"
Moment-timezone cannot do this on it's own as its function which used to handle this was depreciated because it did not work under all circumstances: https://github.com/moment/moment/issues/162 to get the timezone abbreviation client side.
For a crossbrowser support I recommend using YUI 3 Library:
Y.DataType.Date.format(new Date(), {format:"%Z"});
It supports strftime identifiers.
For more information:
http://yuilibrary.com/yui/docs/datatype/#dates
I know the problem remains of differences between browsers, but this is what I used to get in Chrome. However it is still not an abbreviation because Chrome returns the long name.
new Date().toString().replace(/^.*GMT.*\(/, "").replace(/\)$/, "")
Not possible with vanilla JavaScript. Browsers are inconsistent about returning timezone strings. Some return offsets like +0700 while others return PST.
It's not consistent or reliable, which is why you need 3rd party script like moment.js (and moment-timezone.js) or create your own hashtable to convert between offsets and timezone abbreviations.
This is a tricky subject. From what I gather the timezone is not embedded as part of the Date object when it's created. You also cannot set the timezone for a Date object. However, there is a timezone offset you can get from a Date object which is determined by the user's host system (timezone) settings. Think of timezone as a way to determine the offset from UTC.
To make life easier, I highly recommend moment and moment-timezone for handling these things. Moment creates a wrapper object for Date with a nice API for all kinds of things.
If an existing date object is supplied to you through some parameter or something, you can pass it the constructor when creating a the moment object and you're ready to roll. At this point you can use moment-timezone to guess the user's timezone name, and then use moment-timezone formatting to get the abbreviation for the timezone. I would venture to say that most users have their timezone set automatically but you shouldn't rely on this for 100% accuracy. If needed you can also set the timezone you want to use manually before pulling the format you need.
In general when working with date and time it's best to store UTC in your database and then use moment js to format the time for the user's timezone when displaying it. There may be cases where you need to be sure the timezone is correct. For example if you are allowing a user to schedule something for a specific date and time. You would need to make absolutely sure that with a west coast user that you set the timezone to PDT/PST before converting to UTC for storage in your database.
Regarding the timezone abbreviation...
Here is a basic example to get the timezone abbreviation using moment and moment-timezone.
// if all you need is the user's timezone abbreviation you don't even need a date object.
const usersTimezoneName = moment.tz.guess()
const timezoneAbbr = moment().tz(usersTimezoneName).format('z')
console.log(timezoneAbbr) // PST (depending on where the user is)
// to manually set the timezone
const newYorkAbbr = moment(dateObj).tz('America/New_York').format('z')
console.log(newYorkAbbr) // EST
For displaying a specific date object with offsets for a specific timezone you can do this.
const xmas = new Date('December 25, 2017 16:20:00')
const losAngelesXmas = moment(xmas).tz('America/Los_Angeles')
console.log(losAngelesXmas.format("dddd, MMMM Do YYYY, h:mm:ss a")) // Monday, December 25th 2017, 4:20:00 pm
Try this function
function getTimezoneAbbreviation(date) {
// Convert the date into human readable
// An example: Fri Jul 09 2021 13:07:25 GMT+0200 (Central European Summer Time)
// As you can see there is the timezone
date = date.toString();
// We get the timezone matching everything the is inside the brackets/parentheses
var timezone = date.match(/\(.+\)/g)[0];
// We remove the brackets/parentheses
timezone = timezone.replace("(", "").replace(")", "");
// A new variable for the abbreviation
var abbreviation = "";
// We run a forEach dividing the timezone in words with split
timezone.split(" ").forEach((word) => {
// We insert the first letter of every word in the abbreviation variable
abbreviation += word.split("")[0];
});
// And finally we return the abbreviation
return abbreviation;
}
Try Google's Closure Class goog.i18n.DateTimeSymbols and their locale related classes.
Here is a JavaScript self-updating, 12-hour format date/time display that doesn't quite answer the question, however it may help others as it is related and builds on Stephen DuMont's solution and MDN link. W3 Schools had a very helpful tutorial, and real-time updates do not require page refresh.
Tests with the latest versions of desktop FireFox, Chrome, Opera, and Internet Explorer 11 all work. The "2-digits" hour only appears to prefix a zero for single values in IE, however the minutes return a 2-digit value reliably for all browsers. Tests with discontinued Windows Safari work although 12-hour format is ignored and seconds are not hidden.
The function includes the local timezone, as well adjustable options for fall-back languages, day and date display, and 12/24 hour format. Date and time were split to add the separating 'at' string. Setting only 'toLocaleTimeString' with select options will also return both date and time. The MDN pages can be referenced for options and values.
<!--
function dateTimeClock() {
var date = new Date();
document.getElementById('timedate').innerHTML = date.toLocaleDateString(['en-us', 'en-GB'], {
weekday: 'long',
month: 'long',
day: '2-digit',
year: 'numeric'
}) + ' at ' +
date.toLocaleTimeString(['en-us', 'en-GB'], {
hour12: 'true',
hour: '2-digit',
minute: '2-digit',
timeZoneName: 'short'
});
var t = setTimeout(dateTimeClock, 500);
}
function start() {
dateTimeClock();
}
window.onload = start;
//-->
<div id="timedate"></div>
import { tz } from 'moment-timezone';
import * as moment from 'moment';
const guess = tz.guess(true); // "Asia/Calcutta"
const zone = tz.zone(guess); // return Zone object
zone.abbr(new Date().getTime()) // "IST"
// once u pass timestamp it'll return timezone abbrevation.
try {
result = /.*\s(.+)/.exec(date.toLocaleDateString(navigator.language, {timeZoneName:'short' }))[1];
} catch(e) {
result = (new Date()).toTimeString().match(new RegExp("[A-Z](?!.*[\(])","g")).join('');
}
console.log(result);