This question already has answers here:
Create a Date with a set timezone without using a string representation
(29 answers)
Closed 4 years ago.
Why does this give me september 30 rather than oct 1?
var dob = new Date("1999-10-01")
console.log(dob.toString())
You are creating a Date new Date("1999-10-01") and parsing it with the method toString() which is using your local timezone:
var dob = new Date("1999-10-01")
console.log(dob)
console.log(dob.toISOString())
console.log('My local time is different!')
console.log(dob.toLocaleString('es-AR', { timeZone: 'America/Buenos_Aires', timeZoneName: 'long'}))
console.log('Your local time is different?')
console.log(dob.toString())
The format you are using is a subset of ISO 8601
When no timezone designator is specified offset Zulu (UTC) is implied in the date constructor.
http://www.ecma-international.org/ecma-262/5.1/#sec-15.9.1.15
All numbers must be base 10. If the MM or DD fields are absent “01” is
used as the value. If the HH, mm, or ss fields are absent “00” is used
as the value and the value of an absent sss field is “000”. The value
of an absent time zone offset is “Z”.
In other words, the format that you are using is valid and it denotes a date-time in UTC. What you are seeing in the console is that time represented in your timezone.
const date = new Date("1999-10-01");
console.log(date.toLocaleDateString('ar-EG'));
console.log(date.toString());
console.log(date.toISOString());
Related
This question already has answers here:
How to ISO 8601 format a Date with Timezone Offset in JavaScript?
(21 answers)
Javascript date format like ISO but local
(12 answers)
Closed last year.
Hi i have a date that arrive with this format 2020-05-25T20:11:38Z, and i need to convert to 2020-05-25T21:11:38+01:00.
In my project is not installed moment.js is a big project, and the masters don't use it.
is there some where to make this change?
I have the timeZone for every zone.
I know that there is options like this getTimezoneOffset();
And i did find in stackoverflow, but i didn't find any response in javascript to change zulu to utc with offset.
Thanks for your indications
The format "2020-05-25T20:11:38Z" is a common standard ISO 8601 format, it is also produced by the default Date.prototype.toString method, however it's only with a UTC (+0) offset.
The above ISO 8601 format is reliably parsed by reasonably current built–in parsers (some very old implementations won't parse it correctly), so to get a Date object:
let date = new Date('2020-05-25T20:11:38Z');
Formatting it for a fixed +1 offset can done by adjusting the Date for the offset then formatting it as required by leveraging the default toISOString method, e.g.
// Initial timestamp
let s = '2020-05-25T20:11:38Z'
// Convert s to a Date
let d = new Date(s);
// Show that it's the same date
console.log(`Initial value: ${s}\n` +
`Parsed value : ${d.toISOString()}`);
// Create a new date with 1 hour added as 3,600,000 milliseconds
let e = new Date(d.getTime() + 3.6e6);
// Format and manually modify the offset part
let timestamp = e.toISOString().replace('Z','+01:00');
console.log(`Adjusted timestamp: ${timestamp}`);
// Parse back to date
console.log(`Parsed to a Date : ${new Date(timestamp).toISOString()}`);
The resulting timestamp can be parsed back to a Date that represents the same instant in time as the original string (last line).
Note that the adjusted Date is only created for the sake of formatting the timestamp, it shouldn't be used for anything else.
If, on the other hand, you want a general function to format dates as ISO 8601 with the local offset, there is likely an answer at Javascript date format like ISO but local that suits. If so, then this is a duplicate, e.g. this answer or this one.
Also, there are a number of libraries that will allow specifying the formatting and timezone as separate parameters, so consider using one if you're going to do a lot of date formatting or manipulation.
This question already has answers here:
How to initialize a JavaScript Date to a particular time zone
(20 answers)
How do I specify the time zone when creating a JavaScript Date?
(1 answer)
Closed 1 year ago.
I have developed a page where users can filter records based on their selections in the filters.
The datetime picker allows users to select a specific datetime and a dropdown allows the user to select the time zone in which they want that selected date to be converted to UTC.
For example, on my computer the time zone set is Asia/Karachi which has an offset of +5 UTC.
But I want to select Europe/Prague from the dropdown and 09/14/2021 3.30pm as the date time. The time should be converted to 1.20 PM as Europe/Prague has a time offset of +2 from UTC using below code.
var ddate = new Date(date.toLocaleString('en-US', {
timeZone: 'Europe/Prague'
}));
However, this yields 12.30 PM as the time. Apparently it is converting from Asia/Karachi(my computer time zone) to Europe/Prague. But I want the selected datetime to be converted to UTC based on the time zone the user selects from the dropdown of available time zones.
Is there any possible solution? I have tried researching and coding a lot but haven't found any yet.
Have you tried moment & moment-timezone?
maybe something like this:
import moment from "moment";
const myDate = "09/14/2021 3:30 PM";
const myTimeZone = "Europe/Prague";
let convertedTime = moment.tz(myDate, time_zone).format();
and you can set your format to be ("HH:mm A")
If you want a date constructor for specific timezones make use of new Date('YYYY-MM-DDTHH:NN:SS.sss±HH:NN').
What you describe and want, is what Date already does if you generate a Date using new Date('YYYY-MM-DDTHH:NN:SS.sss±HH:NN'). You simply have to use it in this format.
±HH:NN is timezone information from your timezone-dropdown. It can either start with a + or a -. (Take a look at the 3rd snippet)
Other formats as the ones i mentioned, are invalid if passed to the Date constructor and you may get unexpected results.
The dropdown (the one about the timezone) requires the information of +hrs:mins and -hrs:mins respective to the timezone selected.
The following describes the Date constructor.
Don't pass a formated string like this to new Date() - it's invalid.
If you use new Date() you either have to pass a time value in milliseconds, a date only or an ISO Timestamp.
new Date(date.valueOf()) results in a copy
new Date(date.toISOString()) results in a copy
new Date(date.toJSON()) results in a copy
new Date(date.toDateString()) results in a copy of the date only => no hour GMT +0 on the current day.
All examples above (except the last one) are a copy of the original date.
For more information on the arguments supported by the Date-constructor take a look at Date.parse()#Date Time String Format
There is no need to change anything. If it's midnight at Asia/Karachi, it will be 9pm (21:00) in Europe/Prague.
As you can see on this example, use GMT+0 or any other accepted Time-Zone String.
Examples of different arguments
1
const date = new Date("2021-02-14T00:00:05.000+00:00"); // 5 seconds after midnight on February 14th, 2021 GMT+0
["GMT+0", "UTC", "America/New_York", "Europe/Madrid", "Europe/Prague", "Europe/Moscow", "Asia/Karachi", "Asia/Tokyo", "PRC"].forEach(timeZone => {
console.log(timeZone, date.toLocaleString('en-US', { timeZone }))
});
2
const date = new Date("2021-09-14");
["GMT+0", "UTC", "America/New_York", "Europe/Madrid", "Europe/Prague", "Europe/Moscow", "Asia/Karachi", "Asia/Tokyo", "PRC"].forEach(timeZone => {
console.log(timeZone, date.toLocaleString('en-US', { timeZone }))
});
3
// 16:00 at timezone +9 is 7 am at gmt
const date = new Date("2021-09-14T16:00:00.000+09:00");
["GMT+0", "UTC", "America/New_York", "Europe/Madrid", "Europe/Prague", "Europe/Moscow", "Asia/Karachi", "Asia/Tokyo", "PRC"].forEach(timeZone => {
console.log(timeZone, date.toLocaleString('en-US', { timeZone }))
});
This question already has answers here:
Why does Date.parse give incorrect results?
(11 answers)
Closed 3 years ago.
I have an input="date" of which i am trying to pull the day, month, and year individually and it seems to be off by a day or so. For example if i Put in 01/01/1900 it seems to be spitting back out 1899 11 31. So for a basic example I have -
function clickDate() {
const dateinput = document.querySelector(".date").value;
const dateObj = new Date(dateinput);
console.log("pull date", dateObj.getFullYear(), dateObj.getMonth(), dateObj.getDate());
};
<input class="date" type="date">
<button onClick="clickDate()"> format</button>
you can see if you input 01/01/1900 the console outputs "pull date" 1899 11 31". Unsure what i am overlooking here.
Your issue lies with UTC versus local timezone offsets.
Using the built–in parser, a string in the format YYYY-MM-DD is interpreted as UTC, whereas other strings will be interpreted as local.
Use of the built–in parser is discouraged:
Note: Parsing of date strings with the Date constructor (and Date.parse(), which works the same way) is strongly discouraged due to browser differences and inconsistencies. Support for RFC 2822 format strings is by convention only. Support for ISO 8601 formats differs in that date-only strings (e.g. "1970-01-01") are treated as UTC, not local. (mdn)
On the other hand, getFullYear, getMonth, and getDate etc. return local values.
Here is a demonstration:
const dateInput = '2019-02-05'
const dateObj = new Date(dateInput); // parsed as UTC
console.log("pull date", dateObj.getUTCFullYear(), dateObj.getUTCMonth(), dateObj.getUTCDate()); // UTC
console.log("pull date", dateObj.getFullYear(), dateObj.getMonth(), dateObj.getDate()); // local
You have two choices:
1) The simplest being stick with the getUTC... functions.
2) If that doesn't work because you need to return the date object or manipulate it, then parse the input value and construct Date using individual year, month, day. This works because when using this constructor, the inputs are interpreted as local.
const dateInput = '2019-02-05';
let dateParts = dateInput.split('-');
dateParts[1]--; // month in Date constructor is 0-indexed (e.g. '02' represents March);
const dateObj = new Date(...dateParts); // parsed as local
console.log("pull date", dateObj.getUTCFullYear(), dateObj.getUTCMonth(), dateObj.getUTCDate()); // UTC
console.log("pull date", dateObj.getFullYear(), dateObj.getMonth(), dateObj.getDate()); // local
This question already has answers here:
Why does Date.parse give incorrect results?
(11 answers)
Closed 5 years ago.
I am creating a new date from string
var s = "2017-12-06"
var dt = new Date(s)
console.log(dt) // outputs Tue Dec 05 2017 19:00:00 GMT-0500 (EST)
What am I missing ?
Date.toString() is formatted in your local time zone, but because you've passed in an ISO-8601 string, the value is parsed as if it's UTC.
From the Date.parse() documentation (as the Date(String) constructor is documented to behave like Date.parse):
The date time string may be in a simplified ISO 8601 format. For example, "2011-10-10" (just date) or "2011-10-10T14:48:00" (date and time) can be passed and parsed. Where the string is ISO 8601 date only, the UTC time zone is used to interpret arguments. If the string is date and time in ISO 8601 format, it will be treated as local.
So you'll end up with a Date which is equivalent to 2017-12-06T00:00:00Z. But Date.toString() shows you that instant in time in your current time zone - and if you're in America/New_York or a similar time zone which is 5 hours behind UTC at that moment in time, that means it'll print December 5th at 7pm.
This question already has answers here:
Why does Date.parse give incorrect results?
(11 answers)
Changing the format of a date string
(2 answers)
Closed 5 years ago.
I am trying to use a simple date function in my application to pass a date in the format of yyyy-mm-dd such as 2017-07-30 and have it returned in the format of 07/30/2017.
However, when I try this, I supply my date correctly but it outputs one day shorter than what I am looking for.
function format(inputDate) {
var date = new Date(inputDate);
if (!isNaN(date.getTime())) {
var day = date.getDate().toString();
var month = (date.getMonth() + 1).toString();
// Months use 0 index.
return (month[1] ? month : '0' + month[0]) + '/' +
(day[1] ? day : '0' + day[0]) + '/' +
date.getFullYear();
}
}
console.log(format('2017-07-30'));
Here is a fiddle: http://jsfiddle.net/49pptrj4/
Any thoughts as to why this is returning incorrectly?
Result on my end:
From here
Given a date string of "March 7, 2014", [Date.]parse() assumes a local time zone, but given an ISO format such as "2014-03-07" it will assume a time zone of UTC.
Your date string is assumed to be 0:00, or midnight, on the date specified in UTC, the time zone of Greenwich, England. Your browser however takes this time and converts it to your local timezone, which is a few hours behind UTC if you're in the Americas, making the result a day behind.
The following code should work for creating a Date in the local timezone with the correct date.
utcDate = new Date("2017-07-30"); //Date object a day behind
new Date(utcDate.getTime() + utcDate.getTimezoneOffset() * 60000) //local Date
Here the local Date is created by adding time based on the time zone difference. getTimezoneOffset() returns in minutes, so * 60000 is needed to convert to milliseconds.
This might not work in areas ahead of UTC; it might advance an extra day.
Edit: Just checked and getTimezoneOffset() is negative in areas ahead of UTC so it will subtract time correctly.