A JavaScript date is fundamentally specified as the time in milliseconds that has elapsed since the epoch, which is defined as the midnight at the beginning of January 1, 1970, UTC (equivalent to the UNIX epoch). This timestamp is timezone-agnostic and uniquely defines an instant in history.
Note: While the time value at the heart of a Date object is UTC, the basic methods to fetch the date and time or its components all work in the local (i.e. host system) time zone and offset.
A date is represented internally as a single number, the timestamp. When interacting with it, the timestamp needs to be interpreted as a structured date-and-time representation. There are always two ways to interpret a timestamp: as a local time or as a Coordinated Universal Time (UTC), the global standard time defined by the World Time Standard. The local timezone is not stored in the date object, but is determined by the host environment (user's device).
When a segment overflows or underflows its expected range, it usually "carries over to" or "borrows from" the higher segment. For example, if the month is set to 12 (months are zero-based, so December is 11), it become the January of the next year. If the day of month is set to 0, it becomes the last day of the previous month. This also applies to dates specified with the date time string format.
There are many ways to format a date as a string. The JavaScript specification only specifies one format to be universally supported: the date time string format, a simplification of the ISO 8601 calendar date extended format. The format is as follows:
Date.parse() and the Date() constructor both accept strings in the date time string format as input. Furthermore, implementations are allowed to support other date formats when the input fails to match this format.
When a segment overflows or underflows its expected range, it usually \"carries over to\" or \"borrows from\" the higher segment. For example, if the month is set to 12 (months are zero-based, so December is 11), it become the January of the next year. If the day of month is set to 0, it becomes the last day of the previous month. This also applies to dates specified with the date time string format.
Note: To generate a timestamp from a string representation of the date, you may be able to use strtotime(). Additionally, some databases have functions to convert their date formats into timestamps (such as MySQL's UNIX_TIMESTAMP function).
So if your business has been around for some time, adding the open date can help encourage a searcher to click on your listing and potentially call or visit your location, hopefully ultimately leading to a sale.
A naive object does not contain enough information to unambiguously locateitself relative to other date/time objects. Whether a naive object representsCoordinated Universal Time (UTC), local time, or time in some other timezone ispurely up to the program, just like it is up to the program whether aparticular number represents metres, miles, or mass. Naive objects are easy tounderstand and to work with, at the cost of ignoring some aspects of reality.
For applications requiring aware objects, datetime and timeobjects have an optional time zone information attribute, tzinfo, thatcan be set to an instance of a subclass of the abstract tzinfo class.These tzinfo objects capture information about the offset from UTCtime, the time zone name, and whether daylight saving time is in effect.
Only one concrete tzinfo class, the timezone class, issupplied by the datetime module. The timezone class canrepresent simple timezones with fixed offsets from UTC, such as UTC itself orNorth American EST and EDT timezones. Supporting timezones at deeper levels ofdetail is up to the application. The rules for time adjustment across theworld are more political than rational, change frequently, and there is nostandard suitable for every application aside from UTC.
An abstract base class for time zone information objects. These are used by thedatetime and time classes to provide a customizable notion oftime adjustment (for example, to account for time zone and/or daylight savingtime).
Return a string representing the date, controlled by an explicit format string.Format codes referring to hours, minutes or seconds will see 0 values.See also strftime() and strptime() Behavior and date.isoformat().
Same as date.strftime(). This makes it possible to specify a formatstring for a date object in formatted stringliterals and when using str.format().See also strftime() and strptime() Behavior and date.isoformat().
Because naive datetime objects are treated by many datetime methodsas local times, it is preferred to use aware datetimes to represent timesin UTC. As such, the recommended way to create an object representing thecurrent time in UTC is by calling datetime.now(timezone.utc).
Because naive datetime objects are treated by many datetime methodsas local times, it is preferred to use aware datetimes to represent timesin UTC. As such, the recommended way to create an object representing aspecific timestamp in UTC is by callingdatetime.fromtimestamp(timestamp, tz=timezone.utc).
Return a datetime corresponding to the ISO calendar date specifiedby year, week and day. The non-date components of the datetime are populatedwith their normal default values. This is the inverse of the functiondatetime.isocalendar().
datetime2 is a duration of timedelta removed from datetime1, moving forward intime if timedelta.days > 0, or backward if timedelta.days < 0. Theresult has the same tzinfo attribute as the input datetime, anddatetime2 - datetime1 == timedelta after. OverflowError is raised ifdatetime2.year would be smaller than MINYEAR or larger thanMAXYEAR. Note that no time zone adjustments are done even if theinput is an aware object.
Computes the datetime2 such that datetime2 + timedelta == datetime1. As foraddition, the result has the same tzinfo attribute as the inputdatetime, and no time zone adjustments are done even if the input is aware.
If both are naive, or both are aware and have the same tzinfo attribute,the tzinfo attributes are ignored, and the result is a timedeltaobject t such that datetime2 + t == datetime1. No time zone adjustmentsare done in this case.
If both are aware and have different tzinfo attributes, a-b actsas if a and b were first converted to naive UTC datetimes first. Theresult is (a.replace(tzinfo=None) - a.utcoffset()) - (b.replace(tzinfo=None)- b.utcoffset()) except that the implementation never overflows.
If both comparands are aware, and have the same tzinfo attribute, thecommon tzinfo attribute is ignored and the base datetimes arecompared. If both comparands are aware and have different tzinfoattributes, the comparands are first adjusted by subtracting their UTCoffsets (obtained from self.utcoffset()).
Return a datetime with the same attributes, except for those attributes givennew values by whichever keyword arguments are specified. Note thattzinfo=None can be specified to create a naive datetime from an awaredatetime with no conversion of date and time data.
If called without arguments (or with tz=None) the system localtimezone is assumed for the target timezone. The .tzinfo attribute of the converteddatetime instance will be set to an instance of timezonewith the zone name and offset obtained from the OS.
If self.tzinfo is tz, self.astimezone(tz) is equal to self: noadjustment of date or time data is performed. Else the result is localtime in the timezone tz, representing the same UTC time as self: afterastz = dt.astimezone(tz), astz - astz.utcoffset() will havethe same date and time data as dt - dt.utcoffset().
If you merely want to attach a time zone object tz to a datetime dt withoutadjustment of date and time data, use dt.replace(tzinfo=tz). If youmerely want to remove the time zone object from an aware datetime dt withoutconversion of date and time data, use dt.replace(tzinfo=None).
where yday = d.toordinal() - date(d.year, 1, 1).toordinal() + 1is the day number within the current year starting with 1 for January1st. The tm_isdst flag of the result is set according to thedst() method: tzinfo is None or dst() returnsNone, tm_isdst is set to -1; else if dst() returns anon-zero value, tm_isdst is set to 1; else tm_isdst isset to 0.
Because naive datetime objects are treated by many datetime methodsas local times, it is preferred to use aware datetimes to represent timesin UTC; as a result, using datetime.utctimetuple() may give misleadingresults. If you have a naive datetime representing UTC, usedatetime.replace(tzinfo=timezone.utc) to make it aware, at which pointyou can use datetime.timetuple().
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