i have a date string on NodeJS
2019-02-25T09:00:00Z
I create a moment object, and set the timezone to new york
let a = moment.tz("2019-02-25T09:00:00Z", "America/New_York");
I then create another moment object, with the same time, but set a different place, arizona
let b = moment.tz("2019-02-25T09:00:00Z", "America/Phoenix");
console.log(a.diff(b));
prints out 0 milliseconds. i would expect expect to get 7200000 (2 hour time difference). why am i not getting this difference?
"2019-02-25T09:00:00Z" means "9am on February 25th 2019, UTC". The "Z" part is what indicates that the value is in UTC.
You've created two values representing the same instant in time, but in two different time zones - so they'll have different local values, but they both represent the same instant, so the difference between them is 0.
If you want to create a value which represents "9am on February 25th 2019, in the given time zone" then just remove the Z. (I don't know what Moment does if the value you specify is either ambiguous or skipped due to offset changes in the time zone, but that's something you should investigate if you're going to do this with arbitrary data.)
Related
The Microsoft planner does not seem to support time for tasks, i.e. does not have any way to specify the time:
But when I am calling planner API to get task start date/time like this:
https://graph.microsoft.com/v1.0/planner/plans/xxxxxxxxxx/tasks
The API returns dates with time (and the time is not zero and not UTC-zero). In this example, it's 10:00. Where is this 10:00 coming from? May it be hardcoded in planner?! My local time when I created that task was 18:23
Basically, the question is, what is this time (may it be different in different organizations / teams)? Or more specifically, how do I get pure date (the date displayed by the planner itself) from that value? Removal of the time seems to be a wrong option? (the time may be overlapping to the next / previous day, depending on the time zone). In which time zone is the time, returned by the planner API? Why is it not zero (or UTC-zero), if planner supports only dates?
Planner stores the date picked in the UI as 10 AM UTC of the picked date. That specific value causes the Local time equivalent to be in the same date as most places. The recommendation for clients is to take the time value with it's offset (in cases Planner Web sets this, the offset will be 0, which is indicated by the Z suffix in your sample), and convert it to local time to display (just the date portion of the resulting value).
startDateTime is the property of type DateTimeOffset representing date and time at which the task starts. The Timestamp type represents date and time information using ISO 8601 format and is always in UTC time. For example, midnight UTC on Jan 1, 2014 is 2014-01-01T00:00:00Z
Refer documentation here.
Thanks.
I'm speccing an application that displays time periods to the user. The goal is to present periods in a simple view (no time, no timezones) and detailed view (date and time, with timezone data). The simple view should be unambiguous, in other words the user can glance at it and their assumptions about what they see are correct (they are valid in the local timezone).
For the end of the global period, displaying the date in the AoE timezone [1] will solve this problem. For example, a submission deadline might display as 2018-04-03 (actually 2018-04-03 23:59:59 AoE). This means submissions are accepted as long as it is April 3 somewhere on the planet.
But I also want to indicate that start of a global period. For example, if submissions open on April 2 2018 00:01, they are accepted as soon as it is April 2 somewhere on the planet. (This would currently be at UTC+14, matching the Line Islands.)
I can't see a way to use AoE to derive a global start time. Is there an equivalent to AoE (a standardized semantic timezone) that tracks the global start time?
Notes:
Hardcoding UTC-12 and UTC+14 is the simple answer for the modern day. But I'm looking for semantic timezones that would be updated if the values changed (and not reference non-existent historical datetimes).
I thought I'd seen Etc/AoE in the tz database but this is not the case.
References:
AoE
UTC-12:00
UTC+14:00
[1] The Anywhere on Earth (AoE) timezone represents the moment a datetime expires "anywhere on Earth". It currently matches time at Howland Island (UTC-12). If a UTC-13 timezone were invented, it would be updated to track that.
As far as I could understand, AoE is not a timezone as defined by IANA (AFAIK, a list of all offsets from some geographic region during history).
It's more like a "concept", an idea of a specific date being valid in any place on earth. As you said, this notion of "being valid" will change if more timezones are created or removed.
I don't even know if date/time API's can properly handle AoE automatically - maybe I should study more. But my conclusion is that the only way to achieve your goal is to check manually:
you could check all available timezones and see if the date is valid there, comparing to the current date/time at that zone
you could configure the UTC+14 as the offset to be compared, and make some scheduled job (daily/weekly/every-time-IANA-publishes-a-new-version?) to check all zones and set the correct one (with the biggest offset?). You must also take care if this zone has Daylight Saving changes, because the offset will change as well (and what to do with overlaps, when clocks shift 1 hour back and a local time may exist twice?)
I am new to this iOS world, trying to learn how to handle dates and time.
Imagine I have a Class Shop. The shop have time-intervals which represent the open and close time for each day of the week.
Some context data (example string from database, GMT Timezone):
Monday: "08:00:00-13:00:00, 15:00:00-18:00:00"
Tuesday:"09:00:00-13:00:00, 15:00:00-19:00:00"
Wednesday: "15:00:00-23:59:59"
Thursday: "00:00:00-08:00:00"
etc..
Monday for example would have to store 2 time-intervals.
My question is how can I store this data (array of DateIntervals? TimeIntervals? or another more suitable class?) in a Class and get the current time to check if the store is opened or not.
The native date format for iOS (and Mac OS) is the Date object. A Date object represents and instant in time, independent of time zone. You then use a DateFormatter to convert a date to a string representation in a particular time zone.
In your case, though, you need to represent timer ranges for days of the week on a variety of different dates.
You should read the Calendar class reference in the Xcode documentation. Of particular interest would be the date(bySetting:value:of:) method, which will let you start from a given date and calculate a new date by changing the value of various date components.
You have a set of time intervals for each day. So you need a way to store, for a given day of the week, one or more time intervals. Your time intervals have a start time and an end time. Each of those needs to be represented by an hour, minute, and optionally second.
With that information you can get the current date/time and split it into components. Get the weekday, hour, minute, and second. Using the weekday you can get the appropriate time intervals. Then you can iterate those intervals and see if the current hour, minute, second falls between one of the intervals.
This all assumes that for a given business, your time intervals (open times) are specified in local time for the given business.
When converting the current date/time into its components, you should ensure that you set the calendar's timezone to match the timezone of the business in question.
There is no need for any date comparisons for any of this. You want to compare hours/minutes/seconds of the current date with the hours/minutes/seconds of the open times.
I know that I can get browser timezone name: moment.tz.guess()
How can I guess timezone for custom date? e.g. moment("2020-12-30T14:17:40+11:00").tz.guess() ?
You can't. There are 9 different location-based zones that use +11:00 year round, and 5 more that use it for daylight saving time.
You might be able to eliminate a few if the date and time put it into a time zone where daylight time is not in effect and the standard time doesn't match, but from there, the best you could do would be to pick one at random.
See "time zone != offset" in the timezone tag wiki.
Moment-timezone can guess the browser's time zone because it can query the offset for multiple different timestamps, algorithmically reducing the possibilities. Even then, there are often several that could match, and thus the most likely one is picked (based on population statistics). In the end, it's still a guess.
I'm keeping the current date in a model using a datetime field in which I am indicating default to take the current date as a value.
_defaults = {
'f_inicio' : lambda *a: datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
}
Assuming that the current date is '07/10/2013 17:24:05 ', in the view is the date '07/10/2013 12:24:05' and rectified in the database and the date is '07/10/2013 17:24:05'; gather that this subtracting five hours. The user can set the time zone 'America/Bogota', Colombia is in the region (GTM - 5:00). But do not understand how to properly show when the user since I get a totally different value that should show. Apparently this taking as 'GTM 0' the GTM Colombia. Taking the approximate date create_date field that should have given me as default is '2013-10-07 22:24:05.384'.
Anyone have any idea what may be happening, really appreciate any help on this issue that is driving me crazy.
This drived me too crazy in the past. This is a real simple issue.
The date stored in the database is UTC (GMT-0) timezone. Assume that the person is set with timezone GMT - 5:00, then while storing the value to the database, the date will be added with 5 hrs (exactly 5, not little more or little less) and thus we get the UTC time to store into the database. Now when displaying the same it will check for the users timezone and it finds that its GMT - 5:00 so the database time will be subtracted with 5 (again exactly 5, not little more or little less) and displayed the user.
This will be great for system which is used in different timezones. So the understanding is the input is taken in the user's timezone stored in UTC(GMT-0) and displayed to user's timezone (even if the user viewing is in the different timezone the time will be accurate to their timezone)
Note: if the user is not set with the timezone the browsers timezone is considered and will be used with the warning icon on the top corner
That's it. Hope this gives u better clarity!!