weird seconds offset in js date object in chrome - javascript

When looking at the valueOf value of a date object at the beggining of a year i expected to always receive zero seconds.
The following code shows that until 1917 there was an offset of 54 seconds or 40 seconds in chrome. in IE i receive 0 seconds for all years.
Is there a reason for this? it seems to only happen in the last chrome version
for(var i=0; i<2020;i++)
if(!new Date(i,0,1).valueOf().toString().match("00000$"))
console.log({
y:i,
s: new Date(i,0,1).valueOf().toString().match(/(\d{2})\d{3}$/)[1]})

This is Not a BUG..
As #Krzysztof pointed out Chrome has implemented a new spec for timezone offset calculation following the merge of Make LocalTZA take 't' and 'isUTC' and drop DSTA(t) to Ecma 262. So now the time-zone conversion does not work by just backward interval of seconds, it is calculated as what local time was being observed in a specific region.
Explanation:
I am from a wonderful little country called Bangladesh of South-Asia which follows BST(Bangladesh Standard Time +0600 GMT), which was not always exactly 6 hours ahead of GMT. As JavaScript date takes in local time when I print the start time of this year in GMT I get:
new Date(2018, 0, 1).toUTCString()
// "Sun, 31 Dec 2017 18:00:00 GMT"
In 2009 one hour day-light saving was observed in Bangladesh from 19 June to 31 December. So if I print the first day of December 2009 I get:
new Date(2009, 11, 1).toUTCString()
// "Mon, 30 Nov 2009 17:00:00 GMT"
You can see the day-light saving is now reflected in the date now, which is not visible in my nodeJS console. There was also changes in local time in 1941-1942 as shown below and can be seen on timeanddate.com:
All of the changes are reflected in Chrome now:
new Date(1941, 6, 1).toUTCString()
// "Mon, 30 Jun 1941 18:06:40 GMT"
new Date(1941, 11, 1).toUTCString()
// "Sun, 30 Nov 1941 17:30:00 GMT"
new Date(1942, 7, 1).toUTCString()
// "Fri, 31 Jul 1942 18:30:00 GMT"
new Date(1942, 11, 1).toUTCString()
// "Mon, 30 Nov 1942 17:30:00 GMT"
So now if I pick any date before 1941 keeping in mind my local time is 6 hours ahead I see an offset of 6 minutes 40 seconds. It will vary depending on the time-zone for the back dates due to the recent update of Chrome, or specifically saying the update of ECMAScript(JavaScript).

This may not be 100% the solution of the problem, but one can get the "jitter" introduced by chrome by casting it to UTC and back, then compensate with a new new Date(oldDate.getTime() + jitter).
// Compensates for google chrome 67+ issue with very old dates.
// We should skip this test if any other browser.
$getJitter: function (d) {
var utcDate = new Date(Date.UTC(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate(), d.getUTCHours(), d.getUTCMinutes(), d.getUTCMilliseconds())),
jitter = 0;
// As we're setting UTC date, the non-UTC year could be
// shifted one ahead or behind, so set the utc full
// year to ensure compliance.
utcDate.setUTCFullYear(d.getUTCFullYear());
if (d.getFullYear() != utcDate.getFullYear() ||
d.getMonth() != utcDate.getMonth() ||
d.getDate() != utcDate.getDate() ||
d.getHours() != utcDate.getHours() ||
d.getMinutes() != utcDate.getMinutes() ||
d.getMilliseconds() != utcDate.getMilliseconds()) {
// infers the "jitter" introduced during the conversion to compensate in the
// actual value of ticks
jitter = d.getTime() - utcDate.getTime()
}
return jitter;
}
This "jitter" pretty much depends on the time zone. For Brazil I'm getting a 28 seconds noise (so it gets back to like, 12:00:00 AM > 23:59:32 PM the previous day.
For Brazil the issue happens down to 1913. This coincides with the time we got our daylight saving times and time zone to -3:00 from -3:06, according to the time changes over years at https://www.timeanddate.com/time/zone/brazil/sao-paulo.
With the above code you can explore the broken dates with this loop:
for (var i=1900; i < 2020; i++) {
for (var j=0; j < 12; j++) {
var dt = new Date(i, j, 1);
var jitter = System.DateTime.$getJitter(dt);
if (jitter != 0) {
console.log("broken: " + i + ", " + j + ", jitter: " + (jitter/1000) + "s: " + dt.toString());
}
}
}

Related

how to convert date to 20160422060933.0Z format?

In angular I have to save data to database in this time format 20160422060933.0Z ?
Someone told me that this is Microsoft time format. I don't know how to convert date to this format, anyone encountered this before?
2016 is a year, 04 is a month, and 22 is a date but i don't know what 060933.0Z is. We use Dreamfactory API and SQL Server
Later edit: based on another answer, actually this seems to be a standard format colloquially called a "LDAP date". See Converting a ldap date for some details on the format (and how to parse it in Java). It can for sure be easily parsed with any typical JS date library or even without any library.
Let's break it down into pieces.
2016 = full year
04 = month, padded to 2 digits
22 = day of month, likely also padded to 2 digits
06 = hour of day, padded to 2 digits, likely on a 24h scale
09 = minute of the hour, padded to 2 digits
33 = second of the minute, likely padded to 2 digits
. = literal
0 = probably "second fraction"
Z = offset from UTC. Z meaning UTC.
Parsing it
You have several options to parse it:
If you assume you're going to always get an UTC datetime from the backend, you can naively parse it in JavaScript just by extracting the relevant substrings.
const input = '20160422060933.0Z';
new Date(Date.UTC(
input.substr(0, 4), // year
input.substr(4, 2) - 1, // month is 0-indexed
input.substr(6, 2), // day
input.substr(8, 2), // hour
input.substr(10, 2), // minute
input.substr(12, 2), // second
("0." + input.split(/[.Z]/gi)[1]) * 1000 // ms
));
// Fri Apr 22 2016 09:09:33 GMT+0300 (Eastern European Summer Time)
You can be a little creative and actually manipulate the string into an ISO format. Then you can just use the native Date.parse function, which supports parsing ISO strings (other formats are browser-dependent). The advantage is that it'll support dates that are not UTC as well.
new Date(Date.parse(
input.substr(0, 4) + "-" + // year, followed by minus
input.substr(4, 2) + "-" + // month, followed by minus
input.substr(6, 2) + "T" + // day, followed by minus
input.substr(8, 2) + ":" + // hour, followed by color
input.substr(10, 2) + ":" + // minute, followed by color
input.substr(12, 2) + // second
input.substr(14) // the rest of the string, which would include the fraction and offset.
))
// Fri Apr 22 2016 09:09:33 GMT+0300 (Eastern European Summer Time)
Use a library like luxon, momentjs, etc. This you might already have a JS library in your project. You'd need to build a date format pattern to parse this format into a native Date object or some other library-specific object. For example, with momentjs you'd do:
moment("20160422060933.0Z", "YYYYMMDDHHmmss.SZ")
// Fri Apr 22 2016 09:09:33 GMT+0300 (Eastern European Summer Time)
Formatting into it
This side of the operation is even simpler.
Without any date library, you just need to get rid of the "-", ":" and "T" separators from the ISO format. So you can just do the following:
new Date().toISOString().replace(/[:T-]/g, "")
// '20230209175305.421Z'
If you want to use a date library, then you just do the reverse, format operation using the same pattern as for parsing. Eg. in momentjs:
moment(new Date()).utc().format("YYYYMMDDHHmmss.S[Z]")
// "20230209175222.5Z"
(note that I needed to place the "Z" in brackets due to https://github.com/moment/moment-timezone/issues/213).
Just a side note to the other answer here:
You can use ldap2date npm package for parsing, should be not that "heavy" as moment.
Code:
import ldap2date from "ldap2date";
// or import { parse, toGeneralizedTime } from "ldap2date";
const dateString = "20160422060933.0Z";
const date = ldap2date.parse(dateString);
console.log(date.toUTCString());
// Fri, 22 Apr 2016 06:09:33 GMT
const str = ldap2date.toGeneralizedTime(date);
console.log(str);
// 20160422060933Z (note: no period.)
console.log(str.replace("Z", ".0Z"));
// 20160422060933.0Z
function getLdapString(date) {
return ldap2date.toGeneralizedTime(date);
}
const d = new Date();
console.log(getLdapString(d), d.toISOString());
// 20230209181603.965Z 2023-02-09T18:16:03.965Z
And some monkey-patching to match "format":
function getLdapString(date) {
return date.getMilliseconds() !== 0
? ldap2date.toGeneralizedTime(date)
: ldap2date.toGeneralizedTime(date).replace("Z", ".0Z");
}
const d = new Date();
d.setMilliseconds(15);
const d1 = new Date();
d1.setMilliseconds(0);
console.log("Date with milliseconds: ", d.toUTCString(), getLdapString(d));
console.log("Date without milliseconds: ", d1.toUTCString(), getLdapString(d1));
// Date with milliseconds: Thu, 09 Feb 2023 18:22:27 GMT 20230209182227.15Z
// Date without milliseconds: Thu, 09 Feb 2023 18:22:27 GMT 20230209182227.0Z
Or to ignore milliseconds part completelly
function getLdapString(date) {
const copy = new Date(date);
copy.setMilliseconds(0);
return ldap2date.toGeneralizedTime(copy).replace("Z", ".0Z");
}
console.log("Date with milliseconds: ", d.toUTCString(), getLdapString(d));
console.log("Date without milliseconds: ", d1.toUTCString(), getLdapString(d1));
// Date with milliseconds: Thu, 09 Feb 2023 18:29:50 GMT 20230209182950.0Z
// Date without milliseconds: Thu, 09 Feb 2023 18:29:50 GMT 20230209182950.0Z

Unable to get the first day of the Month in Angular 2/4

I'm calculating the dates for my application like date,week,month.
First I am defining day,week,month,custom like:
this.reportTypes = [{TypeId: 1, Type: 'Day'}, {TypeId: 6, Type: 'Week'}, {TypeId: 30, Type: 'Month'}, {
TypeId: 10,
Type: 'Custom'
}]
Next I'm defining dates like:
var currdate = new Date();
if(reportType==1){
// this.reportDataFromDate=currdate;
// this.reportDataToDate=currdate;
//This is for setting the current date
this.reportDataFromDate= currdate;
this.reportDataToDate= currdate;
}
else if(reportType==30){
var First = new Date(currdate.getFullYear(),currdate.getMonth(),1);
this.reportDataFromDate=First;
this.reportDataToDate=currdate;
}
else if(reportType!=10){
var last = new Date(currdate.getTime() - (reportType * 24 * 60 * 60 * 1000));
this.reportDataFromDate=last;
this.reportDataToDate=currdate;
}
}
The problem is after selecting reportType == 30 then it has to get the first day of the month.
It is showing the date as 1-Dec-2017 but it is getting the data of till 30th November 2017?
This is screenshot of the SQL server. I'm sending the date as 1st Dec 2017 but it is getting 30-11-2017.
When the Date() constructor is invoked with integers, the result is a date object with that date assumed your systems (read browser/os) timezone.
Example:
let d = new Date(2017);
// returns Thu Jan 01 1970 01:00:02 GMT+0100 (W. Europe Standard Time)
// and with d.toUTCString(): Fri, 30 Dec 2016 23:00:00 GMT
Which may end up in an entire different year when sending to the server
Using the string constructor and specifying timezone will help you overcome this.
Example:
let d = new Date('2017z');
// returns Sun Jan 01 2017 01:00:00 GMT+0100 (W. Europe Standard Time)
// and with d.toUTCString(): Sun, 01 Jan 2017 00:00:00 GMT
The latter which is what you should pass to a server, and normally do calculations on.
However, note that calculations with dates are a complicated matter best left to a library like moment.js. To get a feel of what you are dealing with have a look at this great talk from the WebRebel conference.
So to actually give an answer to your title, try this example which creates the date in a simple string using UTC:
let d = new Date(currdate.getUTCFullYear() + ' ' +(currdate.getUTCMonth() + 1) + ' 1z');
d.getUTCDay(); // returns the day as an integer where Monday is 0.
Note that we add 1 month due to getUTCMonth() returns January as 0.
Why the difference?
The new Date(x,y,z) constructor treats the parameters as local date values.
See MDB Web Docs - Date
Note: Where Date is called as a constructor with more than one argument, the specifed arguments represent local time. If UTC is desired, use new Date(Date.UTC(...)) with the same arguments.
But, under the hood the date is stored as UTC (milliseconds since 1 Jan 1970).
const date = new Date(2017, 11, 29);
console.log('valueOf()', date.valueOf()) // 1514458800000
and the UTC date is different to your local date (see trailing 'Z' indicates UTC)
const date = new Date(2017, 11, 29);
console.log('date', date) // "2017-12-28T11:00:00.000Z" (trailing 'Z' means UTC)
// The difference in minutes between browser local and UTC
console.log('getTimezoneOffset()', date.getTimezoneOffset() )
and when you send it to the server, JSON sends it as UTC
const date = new Date(2017, 11, 29);
console.log('JSON', date.toJSON())
// JSON will yield string version of UTC === 2017-12-28T11:00:00.000Z
How to fix it
Well, you might decide that you actually want the date/time in local, and conclude it's not broken.
But if you want to send UTC to the server, wrap the parameters in Date.UTC()
const date = new Date(Date.UTC( 2017, 11, 29 ))
console.log('date.toJSON()', date.toJSON() ) // 2017-12-29T00:00:00.000Z
What about month parameter === 11?
From the MDB page referenced above,
Note: The argument month is 0-based. This means that January = 0 and December = 11.
If you are using .Net Web API as backend, you can config the timezone in Web API WebApiconfig.cs like below. It will serialize the time in UTC.
public static void Register(HttpConfiguration config)
{
config.Formatters.JsonFormatter.SerializerSettings.DateTimeZoneHandling = Newtonsoft.Json.DateTimeZoneHandling.Utc;
}
Or use
config.Formatters.JsonFormatter.SerializerSettings.DateTimeZ‌​oneHandling = Newtonsoft.Json.DateTimeZoneHandling.RoundtripKind; //Time zone information should be preserved when converting.

getMonth getUTCMonth difference result

I found and inconsistent result when using the JavaScript date.getMonth() and date.getUTCMonth(), but only with some dates. The following example demonstrates the problem:
<!DOCTYPE html>
<html>
<body onload="myFunction()">
<p id="demo">Click the button to display the month</p>
<script type="text/javascript">
function myFunction()
{
var d = new Date(2012, 8, 1);
var x = document.getElementById("demo");
x.innerHTML=d;
x.innerHTML+='<br/>result: ' + d.getMonth();
x.innerHTML+='<br/>result UTC: ' + d.getUTCMonth();
}
</script>
</body>
</html>
The output of this example is:
Sat Sep 01 2012 00:00:00 GMT+0100 (Hora de Verão de GMT)
result: 8
result UTC: 7
If i change the date to (2012, 2, 1) the output is:
Thu Mar 01 2012 00:00:00 GMT+0000 (Hora padrão de GMT)
result: 2
result UTC: 2
In the first example, getMonth returns 7 and getUTCMonth returns 8. In the second example, both returns the same value 2.
Does anyone already experiences this situation? I am from Portugal and i think that it has something to be with my GMT but i don't understand why this is happening, because the examples are running in same circumstances.
Thanks in advances
You will see that, depending on YOUR TIMEZONE, the console logs may be different. I chose the first of the month '01' because it will be given a midnight default time '00:00:00', which will result in some timezones yielding February instead of March (you can get the full scoop here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/parse) :
let date1 = '2019-03-01'; // defaults to UTC
let date2 = '2019-03-01T14:48:00'; // LOCAL date/time
let dt1 = new Date(date1);
let dt2 = new Date(date2)
let month1 = dt1.getMonth();
let month2 = dt2.getMonth();
console.log("mon1: " + month1);
console.log("mon2: " + month2);
You will find that it is caused by DST difference.
Universal Time Zone date methods are used for working with UTC dates
Date returns month between 0 to 11
new Date(1976, 01 , 18) -
Wed Feb 18 1976 00:00:00 GMT+0530 (India Standard Time)
*getUTCDate return same as getDate() but returns Date based on World Time Zone, same with month and year
new Date(1976, 01 , 18).getUTCDate() -
17
new Date(1976, 01 , 18).getDate() -
18
new Date(1976, 02 , 18).getUTCMonth() -
2
new Date(1976, 01 , 18).getMonth() -
1
new Date(1976, 01 , 18).getYear() -
76
new Date(1976, 01 , 18).getUTCFullYear() -
1976
new Date(1976, 01 , 18).getFullYear() -
1976
A Date in js is just a timestamp, meaning there is no timezone information in any Date instance. A date is an absolute timed event (in opposition to a wall clock time which is relative to your timezone).
So… when you print the date to the console, because there is no timezone information in the date object, it will use your browser's timezone to format the date.
This is embarrassing because if you provide the same date to 2 clients, one in US and the other one in EU and ask them the date's month, because both are using their own timezone, you might end up with different answers.
To prevent this, getUTCMonth(); will use a default timezone of UTC (+0) instead of the client's browser so that the answer will be consistent whatever the client's timezone.

Problem in adding days / month / year to a given date using javascript?

I trying to add days / months / year to a given date and map it to an input field
var d = new Date();
d.setDate(15);
d.setMonth(06);
d.setYear(2011);
document.getElementById("test").innerHTML=d;
d.setDate(d.getDate()+20);
document.getElementById("test").innerHTML+=""+d.getDate()+"/"+d.getMonth()+"/"+d.getYear("YY");
this actually prints out
Fri Jul 15 2011 12:45:48 GMT+0530 (India Standard Time)
4/7/111
actually this is wrong.. it should print out 5/7/2011.. i think by default the system takes as "30" days for a month and adds the +20 days.. but actually Jun has 30 days so that result should be 5/7/2011..
any suggestion about what goes wrong in here.. any alternative for this?
At the first, you have better to use getFullYear to get year as 2011. You did get number from getDate() and add 20. This break Date. You should get long value from getTime(), and add milli-seconds.
<div id="test"></div>
<script>
var d = new Date();
d.setDate(15);
d.setMonth(06);
d.setFullYear(2011);
document.getElementById("test").innerHTML+=" "+d.getDate()+"/"+d.getMonth()+"/"+d.getFullYear();
d.setTime(d.getTime()+1000*60*60*24*20);
document.getElementById("test").innerHTML+=" "+d.getDate()+"/"+d.getMonth()+"/"+d.getFullYear();
</script>
> var d = new Date();
> d.setDate(15);
> d.setMonth(06);
> d.setYear(2011);
is equivalent to:
var d = new Date(2011,6,15); // 15 Jul 2011
Months are zero based (January = 0, December = 11).
Date.prototype.getYear is specified in ECMA-262 ed5 as Return YearFromTime(LocalTime(t)) − 1900. so:
alert(d.getYear()); // 111
whereas:
alert(d.getFullYear()); // 2011
i think by default the system takes as "30" days for a month and adds the +20 days.. but actually May has 31 days so that result should be 5/7/2011.
You are interpreting it a wrong way, Month in a date starts with 0 - Jan..
So as per the date entered by you it comes Jul 15 2011 on the month number 6.
When you add 20 to date it will be Aug 04 2011 and you are directly getting month number which is 7 - i.e. Aug which misleads your calculation. And for the year, yes it is you should getFullYear
Read this to get your basics correct..

Adding a week to Date in JavaScript: rounding error or daylight savings?

I am trying to add seven days to a Data object, however at some stage I start getting strange results.
var currDate = new Date(2011, 2, 28)
, oldTicks = currDate.getTime()
, newTicks = oldTicks + (86400000 * 7)
, nextWeek = new Date(newTicks)
console.log('Old ticks: ' + oldTicks)
console.log('New ticks: ' + newTicks)
console.log('New date : ' + nextWeek)
The output I get, both Chrome/FF is:
Old ticks: 1301230800000
New ticks: 1301835600000
log: New date : Sun Apr 03 2011 23:00:00 GMT+1000 (EST)
Expected to get:
log: New date : Mon Apr 04 2011 23:00:00 GMT+1000 (EST)
As you can see, instead of adding 7 days, just 6 were added. The code above, however, works fine with other dates, say 2011 Apr 28 or 2011 May 28.
Crescent Fresh is correct form what I can deduce.
Looking up timezones GMT+1000 (EST) looks like Australia Eastern Standard Time - from wikipedia - list of timezones by UTC offset
And from wikipedia - daylist savings time around the world, shows that Australia switches from standard to daylight savings time in between the date ranges specified by the OP.
If it were me I'd do:
var curDate = new Date(),
var aWeekLater = new Date(curDate.getFullYear(), curDate.getMonth(), curDate.getDate() + 7);
with some possible adjustments for time of day.
That said, when I try your code in my Chrome developer console, I get 04 Apr as the answer.

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