Unknown date format /Date(1427982649000-0400)/ - javascript

I need to display on the screen some date values but I'm receiving them in a format that I don't know. Does anybody know what format is this and how to convert them?
For example, I'm getting this:
/Date(1427982649000-0400)/
In the database is stored as
2015-04-02 09:50:49.000
I really don't know where to start looking at.

It's a unix timestamp in milliseconds, followed by a timezone (shift in hours differing from UTC).
So, it's UTC -4 hours, 1427982649 seconds after the 1st January of 1970.
Nice little tool for checking unix timestamps : http://www.unixtimestamp.com/index.php (don't forget to convert your milliseconds to seconds before posting them there)
/edit: To add some additional information - the "timezone shift" seems to be following RFC822 (and/or probably some other RFCs), that -0400 can be explained by the syntax "+/-HHMM" specified there, so to be exact it means -04 hours, 00 minutes.

The actual time and date gets converted into the milliseconds, and it follows the Unix time January 1st, 1970.
Because it is the date when the time for the Unix computer started.
But you can convert the milliseconds into the actual time by using some loops or conversions according to that time.

Does anybody know what format is this and how to convert them?
It seems that "/Date(1427982649000-0400)/" is a time value in milliseconds followed by an offset as ±HHmm. To convert that to a Date, use the time value adjusted by the offset.
Assuming the offset uses the typical sign convention, then a positive offset needs to be subtracted and negative offset added to get the correct UTC value, then something like the following should suit:
var s = '/Date(1427982649000-0400)/';
// Get the number parts
var b = s.match(/\d+/g);
// Get the sign of the offset
var sign = /-/.test(s)? -1 : +1;
// Adjust the time value by the offset converted to milliseconds
// and use to create a Date
var ms = +b[0] + sign * (b[1].slice(0,2)*3.6e6 + b[1].slice(-2)*6e4);
console.log(new Date(ms).toISOString()); // 2015-04-02T17:50:49.000Z
In your example, "2015-04-02 09:50:49.000" does not have a timezone, so it represents a different moment in time for each timezone with a different offset. If that is the actual value stored in the database, then I guess the missing timezone is UTC-0800. It is much better to store the values using UTC and to include the offset, then the host timezone is irrelevant.
Things are complicated here because ECMAScript timezone offsets are the opposite sign to the normal convention, i.e. positive for west of Greenwich and negative for east. If that convention is applied, then "/Date(1427982649000-0400)/" converts to 2015-04-02T09:50:49.000Z, which may be what you're after.
If that is the case, just change the sign in the line:
var sign = /-/.test(s)? -1 : +1;
to
var sign = /-/.test(s)? +1 : -1;

Related

How to subtract the time based on the timezone offset

I tried looking for an answer but could not find a particular answer which does with Timezone offset. Hence, posting the same really sorry if there are any answer present already.
I have a requirement in the project where I need to convert the time to UTC or GMT based on the time specified by the user and timezone offset value provided by the user. Basically, the user provides his local time and timezone offset value according to his local time. I need to convert that into UTC/GMT time.
I am using the Node.js and following is the data which is available in the Node.js Backend:
Time: 2020-11-05T15:00:00.000Z
Timezone offset value: +02:00
As the timezone offset value is +02:00 I need to subtract it from the time to convert it into the UTC format. so I can get the time as: 2020-11-05T13:00:00.000Z. I using the moment-js as well. Can someone please help me how can achieve this using the Node.js or using the Moment.js?
If the offset takes daylight saving time into account you should be able to do:
const the_date = '2020-11-05T15:00:00.000';
const offset = 2;
const utc_time = moment.utc(the_date).subtract(offset, 'hours');
It's not clear which way you are trying to convert. If you are converting from UTC to a fixed offset, you can use the utcOffset function, like this:
const m = moment.utc('2020-11-05T15:00:00.000Z').utcOffset('+02:00');
m.format(); //=> "2020-11-05T17:00:00+02:00"
Or - if you were trying to convert from +02:00, then you would include that offset in the input instead of the Z (Z means UTC). You would then just call the utc function, like this:
const m = moment('2020-11-05T15:00:00.000+02:00').utc();
m.format(); //=> "2020-11-05T13:00:00Z"
However you should be aware that an offset is not the same as a time zone. A time zone can have more than one offset, one of which will apply at a given point in time. Those offsets can change due to daylight saving time and for changes in standard time. Thus, asking a user to pick "his timezone offset value according to his local time" is problematic - as you may be applying that offset to the wrong point in time. See "Time Zone != Offset" in the timezone tag wiki for further details.
You should also understand Moment's project status, and possibly choose a different library.
After some more research and trying, I was able to convert it. Posting the answer in addition to Christians response (https://stackoverflow.com/a/64701083/7584240) so if anyone is looking for the answer they will have another option:
var moment = require('moment');
var time = "2020-11-05T15:00:00.000Z";
var timeoffset = "+02:00";
time = moment.utc(time).local().format('YYYY-MM-DDTHH:mm:SS.000');
time = moment(time, 'YYYY-MM-DDTHH:mm:ss.000').subtract(timeoffset).format('YYYY-MM-DDTHH:mm:ss.000') + 'Z';

Formatting a date to the senders local time

I am having a hard time taking a UTC Date string with an offset and adjusting the time to the users local time exactly. I receive a date on our server say: 2017-06-21T20:26:28.744Z and I need to turn it into a timestamp of the senders local time. For the sake of this example lets say the offset is 6 hours.
I know that this is probably wrong and that the z portion explains what the offset really is.
I need to turn 2017-06-21T20:26:28.744Z into 2017-06-21T14:26:28 using moment.
Doing this seems to give me the UTC portion of the string and chops off the offset. I need to use the offset to adjust the hours/ minutes back
moment
.utc('2017-06-21T20:26:28.744Z')
.local()
.format('YYYY-MM-DDTHH:mm:ss')
// 2017-06-21T20:26:28"
// I need 2017-06-21T14:26:28
You can use utcOffset
Setting the UTC offset by supplying minutes. Note that once you set an offset, it's fixed and won't change on its own (i.e there are no DST rules). If you want an actual time zone -- time in a particular location, like America/Los_Angeles, consider moment-timezone.
If the input is less than 16 and greater than -16, it will interpret your input as hours instead.
Here a working sample:
console.log( moment
.utc('2017-06-21T20:26:28.744Z')
.utcOffset(-6)
.format('YYYY-MM-DDTHH:mm:ss') );
<script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>
If you want to use moment-timezone, you can use tz() method:
console.log( moment
.utc('2017-06-21T20:26:28.744Z')
.tz('America/Chicago')
.format('YYYY-MM-DDTHH:mm:ss') );
<script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/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>

Time Zones in Json Date

I am sending Json data via a REST Service to my client. This client should use the data to Display it.
My client uses JavaScript.
I am converting the date in the following way:
var from = new Date(myJsonDate.match(/\d+/)[0] * 1);
The JSON looks like this:
...="From":"\/Date(1450134000000)\/" ...
My problem is that the dates are correct in Germany but are off by one day in Brazil (e.g. showing Sunday instead of Monday in Brazil).
Does this code use time zones and calculates this accordingly?
How could I turn this off?
I want that the date is displayed exactly how i have sent it.
The operations with dates in JavaScript have a time zone variation in which the client machine is configured.
Right opportunity had to fix a function that showed difference between dates and nobody knew because. When you instance a date, the return her appears as: “Thu Feb 14 2008 08:41:27 GMT-0300 (Official Hour of Brazil)”
Note that in date has the GMT (Greenwich Mean Time) that indicates in which time zone the date is configured.
I’ll show as avoid the difference of time caused by this in operations with date. To this we have create a function that convert the date always to the time zone that if wait.
var calculateTimeZone = function(date, offset) {
var miliseconds_with_utc = date.getTime() + (date.getTimezoneOffset() * 60000);
return new Date(miliseconds_with_utc + (3600000 * offset));
}
Note that in the line 3, we invoke the method getTime() that convert the local moment of date to a number represented by miliseconds since January 1st, 1970 (Unix Epoch). We get the current time zone that is set in browser by method geTimezoneOffset() of API the date in JavaScript and we multiply by miliseconds of time of a hour. We add then the two values.
Why a hour?
Why this is the time that represents each time zone. By default this method return this time zone in minutes, by this the convertion in hour is necessary.
For to arrive this number 60000 you have that remember that 1 second have 1000 miliseconds and which 1 minute have 60 seconds, then converting minutes for miliseconds we multiply 60*1000 = 60000.
This moment we have the UTC (Coordinated Universal Time) represented by variable “utc” by sum of local moment the time zone in miliseconds.
We need now get a date starting this UTC added with the time zone of destiny, how by example a date expressed in time zone +5 transforming in time zone of brazil (Hour of Brazilian).
Note that in line 5 we got an offset (Time Zone Representation) in hour and converting to miliseconds. Remember that here 1 second have 1000 miliseconds and which 1 hour have 3600 seconds, then convert hour in miliseconds should multiply 1000 * 3600 = 3600000.
We add this result with the value of variable “utc” and we got the moment to the time zone wanted. Thenceforth we create a new date with based in long appropriate and return this new date.
In this way we can maintain of integrity desired in application when we need expressed a date in right time zone.
Does this code use time zones and calculates this accordingly?
No. Passing a number to the Date constructor is interpreted as a time value, i.e. milliseconds since 1970-01-01T00:00:00Z. Regardless of the settings of the client, it will create a Date for exactly the same instant in time.
However, by default, Date.prototype.toString uses the host system settings to apply an offset to the displayed values as "local" time.
How could I turn this off?
Modify the script engine. It's part of the ECMAScript standard so any implementation that doesn't do it is non–compliant.
I want that the date is displayed exactly how i have sent it.
Either:
Send it as a plain string, not as a date
Also send the time zone offset of the source so you can apply it at the other end to keep the date the same.
ECMAScript offsets have an opposite sense to most standards, they're -ve for east and +ve for west, so to get a Date with local settings that has the same as the source system:
var d = new Date(timevalue);
d.setMinutes(d.getMinutes() + d.getTimezoneOffset() - sourceTimezoneOffset);
Where sourceTimezoneOffset is the offset of the source system in minutes, +ve for west and -ve for east.
Usually dates related to a specific time zone, so as pointed out, the date in one place might be different to the date in another place at the same instant in time.
If you are not doing any modifications in dates when sending it from server side, the date will be in the timezone where the server is hosted.
So, if your server is hosted in Germany, dates will be in Germany's timezone.
There would be 2 ways to solve this:
Send dates to client in user-timezone from server in the response.
Make adjustments in your client application to implement appropriate
date conversion.

Extracting utcOffset from an ISO String with Moment.js

Using moment.js, I'm attempting to extract the offset from an ISO date string so I can use the offset later when formatting an epoch timestamp to ensure the conversion of the timestamp is in the same timezone.
Even though the offset in the string is -0400, the result is always 0;
var currentTime = "2015-03-18T16:10:00.001-0400";
var utcOffset = moment(currentTime).utcOffset(); // 0
I've attempted to use parseZone() as well without success. Is there a way to extract -0400 from the string so I can use it while formatting another time?
Thanks for the help!
KC
The correct way to extract the offset is indeed with parseZone
var currentTime = "2015-03-18T16:10:00.001-0400";
var utcOffset = moment.parseZone(currentTime).utcOffset();
This should result in -240, which means 240 minutes behind UTC, which is the same as the -0400 in the input string. If you wanted the string form, instead of utcOffset() you could use .format('Z') for "-04:00" or .format('ZZ') for "-0400".
The form you gave in the question just uses the computer's local time zone. So it is currently UTC+00:00 in your time zone (or wherever the code is running), that would explain why you would get a zero. You have to use parseZone to retain the offset of the input string.
Also - your use case is a bit worrying. Remember, an offset is not the same thing as a time zone. A time zone can change its offset at different points in time. Many time zones do this to accommodate daylight saving time. If you pick an offset off of one timestamp and apply it to another, you don't have any guarantees that the offset is correct for the new timestamp.
As an example, consider the US Eastern time zone, which just changed from UTC-05:00 to UTC-04:00 when daylight saving time took effect on March 8th, 2015. If you took a value like the one you provided, and applied it to a date of March 1st, you would be placing it into the Atlantic time zone instead of the Eastern time zone.

Why moment.utc(...).diff(moment.utc(...)) gets affected by source date offsets

Check the following code sample:
moment.utc("2014-10-19T09:27:57.9417128+00:00")
.diff(moment.utc("2014-10-19T09:27:57.9417128+02:00"))
I would expect 0 since I'm converting both dates to UTC, but this gives 7200000 as result.
In fact, I'm looking to get moment.fromNow or moment.from to work with UTC in order to get a X seconds/minutes/hours... ago without an invalid result because of Date/moment translating date-times based on the date's offset.
What am I doing wrong here?
I'm not sure why you would think the source offsets should be ignored. They are especially relevant for converting to UTC, because they actually represent the difference between UTC and the time represented.
In the first timestamp, the +00:00 means the time is already at UTC. In the second timestamp, the +02:00 means the time is two hours ahead of UTC. 2 * 60 * 60 * 1000 = 7200000.
In other words:
2014-10-19T09:27:57.9417128+00:00 == 2014-10-19T09:27:57.9417128Z
- 2014-10-19T09:27:57.9417128+02:00 == 2014-10-19T07:27:57.9417128Z
=======================================================================
02:00:00
There is no way the result should be zero, because any way you look at it, the two timestamps represent two different moments in time that are separated by two hours.
Since moment's fromNow function already works with the current UTC time, and you have a full ISO timestamp with an offset, you can just use it directly without any conversion.
moment("2014-10-19T09:27:57.9417128+02:00").fromNow()
You don't even need to convert to UTC first. You could do it like this:
moment.utc("2014-10-19T09:27:57.9417128+02:00").fromNow()
But these will both return the same thing because you have already supplied the offset. They would only differ if you didn't include an offset, in which case the first example would interpret the input string in local time and the second case would interpret the input string in UTC. Neither of which change the behavior of the fromNow function.

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