When I construct a date object from a string, I am getting confusing results. It seems as if the time is chosen arbitrarily (but repeatably) if I don't specify it.
var d1=new Date("2013-10-9"), d2=new Date("2013-10-10");
output = d1+' '+d1.toUTCString()+'<br>\n';
output += d2+' '+d2.toUTCString()+'<br>\n';
Chromium 20.0...
Wed Oct 09 2013 00:00:00 GMT-0600 (MDT) Wed, 09 Oct 2013 06:00:00 GMT
Wed Oct 09 2013 18:00:00 GMT-0600 (MDT) Thu, 10 Oct 2013 00:00:00 GMT
Why would Chromium choose a different time on October 10?
By the way, the workaround is here: https://stackoverflow.com/a/744134/86967
It has to do with the format of the date string you are using. If you specify 2013-10-09 (notice the extra 0 on the day), then it works as expected. If you use 2 digits for the day and month, then you are following the ECMA spec.
var d1=new Date("2013-10-09"), d2=new Date("2013-10-10");
console.log(d1+' '+d1.toUTCString());
console.log(d2+' '+d2.toUTCString());
Yields:
Tue Oct 08 2013 20:00:00 GMT-0400 (Eastern Daylight Time) Wed, 09 Oct 2013 00:00:00 GMT
Wed Oct 09 2013 20:00:00 GMT-0400 (Eastern Daylight Time) Thu, 10 Oct 2013 00:00:00 GMT
I believe the code they are using can be found here:
https://github.com/WebKit/webkit/blob/master/Source/WTF/wtf/DateMath.cpp
When you provide an ECMA date, it will use the parseES5DateFromNullTerminatedCharacters method to parse the date, but when you use a non-standard date format it will use the parseDateFromNullTerminatedCharacters method. I am not that familiar with the webkit code, so I could be wrong, but this is based on my reading of the parsing logic.
The standard date format can be found in section 15.9.1.15 of the ECMA Spec.
Related
I've been struggling for days with some DateTime values.
I have an API backend that uses entity framework and sql server with .netcore.
The big issue when i want to send a datetime from angular to c#
backend. I noticed that Date() in typescript/javascript by default
uses my timezone and i don't know how to exclude it.
For example my date looks like this:
Wed Jul 11 2019 21:00:00 GMT+0300
And when it arrived in c# it becomes 07/10/2010(mm-dd-yyyy), it subtracts 1 day due to timezone.
Is there a way to standardize the Date variable to ignore timezone and always keep the same format DD-MM-YYYY ?
I've also tried to use MomentJS and still can't figure it out, even my MomentJS compares are acting strange due tot his issue.
For example:
const VacationStart = moment(calendarEntity.Vacation.StartTime).utc(false);
const VacationEnd = moment(calendarEntity.Vacation.EndTime).utc(false);
if (VacationStart.isSameOrBefore(ColumnDate,'day') && VacationEnd.isSameOrAfter(ColumnDate,'day')) {
return '#FF0000';
}
In the above example:
VacationStart is Wed Jul 10 2019 21:00:00 GMT+0300
VacationEnd is Wed Jul 17 2019 00:00:00 GMT+0300
ColumnDate is Thu Aug 15 2019 03:00:00 GMT+0300 (incremental value)
Yet for some reason even if i use isSameOrBefore(ColumnDate,'day') to specify to compare only up to days it still does not work. When VacationEnd should be equal to ColumnDate is return false.
Note: everything is in a foreach loop where ColumnDate increases by +1 day.
You just need to use UTC time (Greenwich Mean Time)
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/UTC
https://learn.microsoft.com/en-us/dotnet/api/system.datetime.utcnow?view=netcore-2.2
So something like this:
new Date(new Date().toUTCString()); -- "Mon Jul 01 2019 17:55:41 GMT-0700 (Pacific Daylight Time)"
new Date().toUTCString(); -- "Tue, 02 Jul 2019 00:56:38 GMT"
new Date().toString(); -- "Mon Jul 01 2019 17:57:03 GMT-0700 (Pacific Daylight Time)"
> new Date('2015-1-1')
Thu Jan 01 2015 00:00:00 GMT-0500 (EST)
> new Date('2015-01-1')
Thu Jan 01 2015 00:00:00 GMT-0500 (EST)
> new Date('2015-1-01')
Thu Jan 01 2015 00:00:00 GMT-0500 (EST)
// Yet...
> new Date('2015-01-01')
Wed Dec 31 2014 19:00:00 GMT-0500 (EST)
// Similarly:
> new Date('2015-1-10')
Sat Jan 10 2015 00:00:00 GMT-0500 (EST)
> new Date('2015-01-10')
Fri Jan 09 2015 19:00:00 GMT-0500 (EST)
Can't figure out why this is happening (Chrome 39). Is it related to octal parsing?
Firefox only accepts new Date('2015-01-10'), and returns what I expect: Date 2015-01-10T00:00:00.000Z
Found the answer in a related question; it appears Chrome parses the YYYY-MM-DD format as UTC time, then converts it the local timezone. So, 2015-01-01 00:00:00 in UTC is Dec 31 in EST.
See Inconsistencies when creating new date objects:
It looks like the form '1979-04-05' is interpreted as a UTC date (and then that UTC date is converted to local time when displayed).
Apparently, a possible cross browser solution is to replace the dashes with slashes to force using local time:
new Date('2015-01-10'.replace(/-/g, '/'))
I am unsure of your problem since My chrome(39.0.2171.99) gives me Jan 01 in all case. But having said this, I would like to point out that you should probably use
new Date(2015,1,1)
This is how JS Date is supposed to be initialised.
I got one weird issue with Date object initialization. And wondering if someone can explain why..
var exp1 = new Date('2014-10-17');
var exp2 = new Date(2014,9,17);
var exp3 = new Date('17 Oct 2014');
console.log(exp1);
console.log(exp2);
console.log(exp3);
Results:
Thu Oct 16 2014 18:00:00 GMT-0600 (MDT) // 16th?
Fri Oct 17 2014 00:00:00 GMT-0700 (MST) // Why GMT -7
Fri Oct 17 2014 00:00:00 GMT-0600 (MDT) // The only one that works as expected
Why are these three Date objects so different?
The first date is treated as GMT since no time zone offset is provided. When logged out it shows the time in your local timezone. Adding an offset (exp4 below), I get the date expected.
var exp1 = new Date('2014-10-17');
var exp2 = new Date(2014,9,17);
var exp3 = new Date('17 Oct 2014');
var exp4 = new Date('2014-10-17z-0500');
Results:
Thu Oct 16 2014 19:00:00 GMT-0500 (Central Daylight Time)
Fri Oct 17 2014 00:00:00 GMT-0500 (Central Daylight Time)
Fri Oct 17 2014 00:00:00 GMT-0500 (Central Daylight Time)
Fri Oct 17 2014 00:00:00 GMT-0500 (Central Daylight Time)
I am not sure about exp2 for you, but suspect it has something to do with daylight savings time and that you live in an area that does not observe daylight savings (Arizona?).
Edit: this seems to be browser specific. The results above were generated in Chrome while in IE 11, exp4 was an invalid date. For IE 11 I had to use this format:
var exp4 = new Date('2014-10-17T00:00-05:00');
I'm loading some dates comming from my database into a HTML table in a string format. The string looks like 31-AUG-13 I'm parsing this string into a date object using the below code:
var paymentDate = $(this).find('td.paymentDate').text();
var test = $.datepicker.parseDate('d-M-y', paymentDate);
Everything is ok so far and I'm getting this date object: Date {Sat Aug 31 2013 00:00:00 GMT+0300 (FLE Standard Time)} But once the year is bigger than 2023. In my case 31-JAN-24 and so on it is turning to 1924 and not 2024, so I'm getting these date objects:
Date {Thu Jan 31 1924 00:00:00 GMT+0200 (FLE Daylight Time)}
Date {Fri Feb 29 1924 00:00:00 GMT+0200 (FLE Daylight Time)}
Date {Mon Mar 31 1924 00:00:00 GMT+0300 (FLE Standard Time)}
Date {Wed Apr 30 1924 00:00:00 GMT+0300 (FLE Standard Time)}
And so on. My question is regarding this strange issue. Is there a way to declare the year range and why it is going back to 1900 in the case when the year is bigger than 2023?
This teaches a lesson always use year in full format same was case with y2k problem. Convert date from database in to yyyy format then use it.
I am trying to be able to take many strings with many different formats and in different timezones and turn them into either UTC or my localtime. I have tried the following and for some reason it has given me a hour off:
var moment = require('moment');
console.log(moment('Mon, 30 Sep 2013 18:00:00 EST').format()); //2013-09-30T16:00:00-07:00
console.log(new Date('Mon, 30 Sep 2013 18:00:00 EST')); //Mon Sep 30 2013 16:00:00 GMT-0700 (PDT)
console.log(new Date()); //Mon Sep 30 2013 15:00:00 GMT-0700 (PDT)
The only thing I can think of that could cause this is day light savings time but I am not sure. Any suggestions with how to proceed?
You used the wrong time zone. For an apples-to-apples comparison, use EDT (eastern daylight time):
> console.log(new Date('Mon, 30 Sep 2013 18:00:00 EDT'));
Mon Sep 30 2013 15:00:00 GMT-0700 (PDT)
which is what you would expect (3 hour difference)