I have a list of list of string dates like this: '17/12/2017 19:34'. They are CET dates.
How can I transform it to the user's browser date?
I'm doing this:
const tzGuess = moment.tz.guess()
export const toTimeZone = (time) => {
const format = 'DD/MM/YYYY HH:mm'
return moment(time, format).tz(tzGuess).format(format)
}
console.log(toTimeZone('17/12/2017 19:34', tzGuess))
but how can I say to moment that the date I'm passing at first is a CET one?
Thanks!
You can use moment.tz function for parsing time string using a given timezone (e.g. 'Europe/Madrid').
The issue is: what do you mean with CET? If your input has fixed UTC+1 offset (like Central European Time), then you can use RobG's solution. If you have to consider both CET and CEST, I think that the best soution is to use moment.tz.
Here a live code sample:
const tzGuess = moment.tz.guess()
const toTimeZone = (time) => {
const format = 'DD/MM/YYYY HH:mm'
return moment.tz(time, format, 'Europe/Madrid').tz(tzGuess).format(format)
}
console.log(toTimeZone('17/12/2017 19:34', tzGuess))
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.19.4/moment.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment-timezone/0.5.13/moment-timezone-with-data-2012-2022.min.js"></script>
A great resource about timezone is the timezone tag info page.
Without moment.js, parse the string to a Date, treating it as UTC, then adjust for the CET offset (+0100). You can then format it using local time values for the client:
// Parse date in format DD/MM/YYYY HH:mm
// Adjust for CET timezone
function parseCET(s) {
var b = s.split(/\D/);
// Subtract 1 from month and hour
var d = new Date(Date.UTC(b[2], b[1]-1, b[0], b[3]-1, b[4]));
return d;
}
var s = '17/12/2017 19:34';
console.log(parseCET(s).toString());
However, if the time needs to observe daylight saving (CEST) for the source time stamp, you'll need to account for that.
Related
I have a function in Java to convert an Epoch date to ISO 8601, but I've come across the need to do it in Javascript. I have it somewhat working in JS but it needs to be localized to the timezone.
Java version:
public static String epochToIso8601(long time, String Zone) {
String format = "yyyy-MM-dd'T'HH:mm:ssX";
TimeZone timeZone = TimeZone.getTimeZone(Zone);
SimpleDateFormat sdf = new SimpleDateFormat(format, Locale.getDefault());
sdf.setTimeZone(timeZone);
return sdf.format(new Date(time));
}
Param1: -157737600000
Param2: PST
Output: 1965-01-01T00:00:00-08
My attempt in Javascript:
function epcov(epoch, timezone)
{
var someValueNum = Number(epoch);
var s = new Date(someValueNum);
return s.toISOString();
}
Essentially I want the same thing that's coming out of Java, but it's outputting: 1965-01-01T08:00:00.000Z
By the way, I'm already splitting the date and time up from something that looks like this, so if there is a better to just pass in the following as one string and let Javascript parse it, that would be amazing:
/Date(-157737600000-0800)/
We can convert the string /Date(-157737600000-0800)/ to a unix time (in ms), and a UTC offset in HHMM using String.match().
The HHMM UTC offset can then be converted to a UTC offset in milliseconds by multiplying the HH value by 3600000 and the MM value by 60000.
We then create a new Date object using the unix time and offset values, since we know the exact offset at that point in time.
We then format using Date.toISOString() and replace the 'Z' UTC offset timezone value with the actual UTC offset string (e.g. '-08:00').
function parseAndFormatDate(date) {
const [,millis, offset] = date.match(/([+\-]+\d+)([+\-]+\d+)/);
const offsetMillis = (offset.slice(0, 1) + '1') * (offset.slice(1, 3) * 3600000 + offset.slice(-2) * 60000);
const formattedOffset = offset.slice(0, 3) + ':' + offset.slice(-2);
return new Date(+millis + offsetMillis).toISOString().replace('Z', formattedOffset);
}
console.log(parseAndFormatDate('/Date(-157737600000-0800)/'));
console.log(parseAndFormatDate('/Date(+1664271413000+0100)/'));
.as-console-wrapper { max-height: 100% !important; }
I hope this helps you in some way.
JS doesn't have good (any?!) support for exporting an ISO 8601 string in a specified time zone. So you have to construct the string yourself, manually.
The use of the Swedish locale is to get an ISO 8601-like basis from which to pull the elements of the date time. Unfortunately there is no ISO 8601 formatting locale.
Note that the following will only reliably work with IANA timezone names because timezone abbreviations (PST, CST, BST) can be ambiguous. For example: V8 will accept 'PST' but SpiderMonkey will not.
// Get wall clock date at the specified tz in IS0 8601
const getISO8601Date = (d, timeZone) =>
d.toLocaleString('sv-SE', { timeZone, dateStyle: 'short'})
// Get wall clock time at the specified tz in IS0 8601
const getISO8601Time = (d, timeZone) =>
d.toLocaleString('sv-SE', { timeZone, timeStyle: 'medium'})
// Get time zone offset in specified tz in IS0 8601
const getISO8601TimeZoneOffset = (d, timeZone) => {
const s = d.toLocaleString('sv-SE', { timeZone, timeZoneName: 'longOffset' })
const result = /GMT(?<offset>[+−]\d\d:\d\d)/.exec(s) // Use regexp to pull out offset
return result ? result.groups.offset : 'Z'
}
// Put together an ISO 8601 string representing the wall clock at the specified date, in the specified timezone
const getISO8601Dtg = (instant, timeZone) => {
const d = new Date(instant)
return `${getISO8601Date(d, timeZone)}T${getISO8601Time(d, timeZone)}${getISO8601TimeZoneOffset(d, timeZone)}`
}
// Only reliably accepts IANA timezone names eg. 'America/Los_Angeles'
console.log(getISO8601Dtg(-157737600000, 'America/Los_Angeles')) // 1965-01-01T00:00:00−08:00
Relevant.
in a project we are using momentjs with date. And from backend we become the date in the following format: 2016-10-19T08:00:00Z (don't ask me why...)
Now we are setting a new date in frontend from some selectboxes. And I am trying to convert this in the same format:
const date = '25.03.2021';
const hour = '13';
const minute = '45'; // this 3 values come from value of selectboxes
const rawDate = moment(date).hour(hour).minute(minute);
// trying to convert to 2021-03-25T13:45:00Z
rawDate.format(); // output: 2021-03-25T13:45:00+00:00
rawDate.format('DD.MM.YYYY hh:mm:ss'); // output: 03.01.2022 08:00:00
rawDate.format('DD.MM.YYYY hh:mm:ss z'); // output: 03.01.2022 08:00:00 UTC
rawDate.format('DD.MM.YYYY hh:mm:ss Z'); // output: 03.01.2022 08:00:00 +00:00
rawDate.toISOString(); // output: 2022-01-03T08:00:00.000Z
I know I could probably just use format() or toISOString() and slice/replace the last bit. But I like to know is there a way without any string concat/manipulation?
You could use moment.utc() to ensure your date is in UTC, then use .format() with the format string DD-MM-YYYYTHH:mm:ss[Z].
I'd also suggest explicity defining the format you are parsing from in the moment() call, e.g. pass 'DD.MM.YYYY' as the second argument.
The reason the backend takes dates in this format is that it's a standardized way of formatting dates to make them machine-readable and consistent (ISO 8601)
const date = '25.03.2021';
const hour = '13';
const minute = '45';
// Raw date will be in the UTC timezone.
const rawDate = moment(date, 'DD.MM.YYYY').hour(hour).minute(minute).utc();
console.log(rawDate.format('DD-MM-YYYYTHH:mm:ss[Z]'));
<script src="https://momentjs.com/downloads/moment.js"></script>
You can try convert to UTC ..?
i.e. Do you intend to make use of a UTC date/time..?
const date = '2021-03-25';
const hour = '13';
const minute = '45'; // this 3 values come from value of selectboxes
const rawDate = moment(date).hour(hour).minute(minute);
const utc = moment.utc(rawDate);
console.log(rawDate.format('DD.MM.YYYY hh:mm:ss'));
console.log(utc.format()); //2021-03-25T11:45:00Z
I'm obtaining data.value which is a time in the format: hh:mm a - for example 12:30 am.
I also know:
the local timezone of the user (userTimeZone)
the timezone of the venue (venueTimeZone)
I need to convert the time selected by the user (data.value) to the correct date in the venueTimeZone. For example, if the user is in Americas/New York and they selected 1:30PM on the 20/05/2022, and the venue is in Americas/Los Angeles - the value I am interested in obtaining is 20/05/2022 10:30AM.
This is my attempt, however the timezone itself doesn't change - I think this is because when I create the userDateTime with moment I don't specify a time offset, but I'm not sure how to obtain the offset from userTimeZone, whilst accounting for DST.
const userTimeZone = _.get(
Intl.DateTimeFormat().resolvedOptions(),
['timeZone']
);
const venueDateStr = new Date().toLocaleString('en-US', {
timeZone: venueTimeZone,
});
const Date = new Date(restaurantDateStr);
const venueYear = venueDate.getFullYear();
const venueMonth = `0${venueDate.getMonth() + 1}`.slice(-2);
const venueDateOfMonth = `0${venueDate.getDate()}`.slice(-2);
const userDateTime = createDateAsUTC(
moment(
`${venueDateOfMonth}/${venueMonth}/${venueYear} ${data.value}`,
'DD/MM/YYYY hh:mm a'
).toDate()
).toLocaleString('en-US', { timeZone: venueTimeZone });
EDIT - I do not have the city offset, I have the timezone name, therefore I cannot use any suggested answer which relies on city offset.
Consider using Luxon - the successor to Moment. (See Moment's project status.)
// Parse your input string using the user's local time zone
// (this assumes the current local date)
const local = luxon.DateTime.fromFormat('1:30 pm', 'h:mm a');
// Convert to the desired time zone
const converted = local.setZone('America/Los_Angeles');
// Format the output as desired
const formatted = converted.toFormat('dd/MM/yyyy h:mm a').toLowerCase();
console.log(formatted);
<script src="https://cdnjs.cloudflare.com/ajax/libs/luxon/2.4.0/luxon.min.js"></script>
You could also do this without a library, however you may find that not all browsers will parse the input string, and your output format is up to the browser as well.
// Get the current local date as a string
const date = new Date().toLocaleDateString();
// Parse the date and time in the local time zone
// Warning: This is non-standard and may fail in some environments
const dt = new Date(date + ' 1:30 pm');
// Format the output, converting to the desired time zone
const result = dt.toLocaleString(undefined, { timeZone: 'America/Los_Angeles' });
console.log(result);
There are, of course, manual ways to parse and format dates (using regex, etc.) but I'll leave that up to you or another person to complete.
I have a log file with some timestamps
2020-12-03 08:30:00
2020-12-03 08:40:00
...
I know from the log provider's documentation that the timestamps are written in UTC (although not using ISO format)
Now I want to parse them with date-fns :
const toParse = "2020-12-03 08:40:00"
parse(toParse, 'yyyy-MM-dd HH:mm:ss', new Date()).toISOString()
And because the locale of my computer is in UTC+1 here is what I see:
> "2020-12-03T07:40:00Z"
expected:
> "2020-12-03T08:40:00Z".
Here is the hack I currently use to tell date-fns to parse as UTC :
const toParse = "2020-12-03 08:40:00"
parse(toParse + '+00', 'yyyy-MM-dd HH:mm:ss' + 'X', new Date()).toISOString()
And as expected,
> "2020-12-03T08:40:00Z".
Is there any proper way of doing this using date-fns? Looking for an equivalent to moment's moment.utc()
I don't know about "proper", but you can use zonedTimeToUtc to treat a timestamp as having any offset or timezone you like, including UTC, e.g.
// Setup
var {parse} = require('date-fns');
var {zonedTimeToUtc} = require('date-fns-tz');
// Parse an ISO 8601 timestamp recognised by date-fns
let loc = 'UTC';
let s1 = '2020-12-03 08:30:00';
let utcDate = zonedTimeToUtc(s1, loc);
// Show UTC ISO 8601 timestamp
console.log(utcDate.toISOString()); // "2020-12-03T08:30:00.000Z"
// Parse non–standard format yyyyMMdd
let s2 = '20210119';
let fIn = 'yyyyMMdd';
let d = zonedTimeToUtc(parse(s2, fIn, new Date()), loc);
console.log(d.toISOString()); // "2021-01-19T00:00:00.000Z"```
You can test it at npm.runkit.com/date-fns.
I think you are looking for parseJSON, which supports a number of formats (but does not let you specify the source format).
Converts a complete ISO date string in UTC time, the typical format for transmitting a date in JSON, to a JavaScript Date instance.
import { parseJSON } from 'date-fns';
const utcDate = parseJSON('2020-12-03 08:40:00');
// Thu Dec 03 2020 19:40:00 GMT+1100 (Australian Eastern Daylight Time)
Example of using parse and zonedTimeToUtc
it('should parse polish date', async () => {
expect.assertions(1)
const dateWithoutTime = '29 gru 2003'
const parsed = parse(dateWithoutTime, 'd LLL yyyy', new Date(), {
locale: pl,
})
const dateUTC = zonedTimeToUtc(parsed, 'UTC')
expect(dateUTC.toISOString()).toStrictEqual('2003-12-29T00:00:00.000Z')
})
Probably and easy answer to this but I can't seem to find a way to get moment.js to return a UTC date time in milliseconds. Here is what I am doing:
var date = $("#txt-date").val(),
expires = moment.utc(date);
Any idea what I am doing wrong?
This is found in the documentation. With a library like moment, I urge you to read the entirety of the documentation. It's really important.
Assuming the input text is entered in terms of the users's local time:
var expires = moment(date).valueOf();
If the user is instructed actually enter a UTC date/time, then:
var expires = moment.utc(date).valueOf();
I use this method and it works. ValueOf does not work for me.
moment.utc(yourDate).format()
As of : moment.js version 2.24.0
let's say you have a local date input, this is the proper way to convert your dateTime or Time input to UTC :
var utcStart = new moment("09:00", "HH:mm").utc();
or in case you specify a date
var utcStart = new moment("2019-06-24T09:00", "YYYY-MM-DDTHH:mm").utc();
As you can see the result output will be returned in UTC :
//You can call the format() that will return your UTC date in a string
utcStart.format();
//Result : 2019-06-24T13:00:00
But if you do this as below, it will not convert to UTC :
var myTime = new moment.utc("09:00", "HH:mm");
You're only setting your input to utc time, it's as if your mentioning that myTime is in UTC, ....the output will be 9:00
This will be the answer:
moment.utc(moment(localdate)).format()
localdate = '2020-01-01 12:00:00'
moment(localdate)
//Moment<2020-01-01T12:00:00+08:00>
moment.utc(moment(localdate)).format()
//2020-01-01T04:00:00Z
moment.utc(date).format(...);
is the way to go, since
moment().utc(date).format(...);
does behave weird...
This worked for me. Others might find it useful.
let date = '2020-08-31T00:00:00Z'
moment.utc(moment(date).utc()).format() // returns 2020-08-30T22:00:00Z
If all else fails, just reinitialize with an inverse of your local offset.
var timestamp = new Date();
var inverseOffset = moment(timestamp).utcOffset() * -1;
timestamp = moment().utcOffset( inverseOffset );
timestamp.toISOString(); // This should give you the accurate UTC equivalent.
This moment.utc(stringDate, format).toDate() worked for me.
This moment.utc(date).toDate() not.
here, I'm passing the date object and converting it into UTC time.
$.fn.convertTimeToUTC = function (convertTime) {
if($(this).isObject(convertTime)) {
return moment.tz(convertTime.format("Y-MM-DD HH:mm:ss"), moment.tz.guess()).utc().format("Y-MM-DD HH:mm:ss");
}
};
// Returns if a value is an object
$.fn.isObject = function(value) {
return value && typeof value === 'object';
};
//you can call it as below
$(this).convertTimeToUTC(date);
Read this documentation of moment.js here.
See below example and output where I convert GMT time to local time (my zone is IST) and then I convert local time to GMT.
// convert GMT to local time
console.log('Server time:' + data[i].locationServerTime)
let serv_utc = moment.utc(data[i].locationServerTime, "YYYY-MM-DD HH:mm:ss").toDate();
console.log('serv_utc:' + serv_utc)
data[i].locationServerTime = moment(serv_utc,"YYYY-MM-DD HH:mm:ss").tz(self.zone_name).format("YYYY-MM-DD HH:mm:ss");
console.log('Converted to local time:' + data[i].locationServerTime)
// convert local time to GMT
console.log('local time:' + data[i].locationServerTime)
let serv_utc = moment(data[i].locationServerTime, "YYYY-MM-DD HH:mm:ss").toDate();
console.log('serv_utc:' + serv_utc)
data[i].locationServerTime = moment.utc(serv_utc,"YYYY-MM-DD HH:mm:ss").format("YYYY-MM-DD HH:mm:ss");
console.log('Converted to server time:' + data[i].locationServerTime)
Output is
Server time:2019-12-19 09:28:13
serv_utc:Thu Dec 19 2019 14:58:13 GMT+0530 (India Standard Time)
Converted to local time:2019-12-19 14:58:13
local time:2019-12-19 14:58:13
serv_utc:Thu Dec 19 2019 14:58:13 GMT+0530 (India Standard Time)
Converted to server time:2019-12-19 09:28:13
This worked for me:
const localtime = 1622516400000
moment(localtime).utc(true).format()
We can get 2 UTC date formats.
const date = '2021-07-20T18:30:00Z';
moment.utc(moment(date).utc()).format(); // 2021-07-19T18:30:00Z
moment.utc(moment(date).utc()).toISOString(); // 2021-07-20T18:30:00.000Z (Complete ISO-8601)
This works in my case.
Library: "moment": "^2.29.1",
moment().utc().format()
Don't you need something to compare and then retrieve the milliseconds?
For instance:
let enteredDate = $("#txt-date").val(); // get the date entered in the input
let expires = moment.utc(enteredDate); // convert it into UTC
With that you have the expiring date in UTC.
Now you can get the "right-now" date in UTC and compare:
var rightNowUTC = moment.utc(); // get this moment in UTC based on browser
let duration = moment.duration(rightNowUTC.diff(expires)); // get the diff
let remainingTimeInMls = duration.asMilliseconds();