Custom Calendars in JS/WASM

Adding new calendars to Calends is a fairly straightforward process. Extend the CalendarDefinition() abstract class, and implement three methods. Then, simply construct an instance of your calendar system, and Calends will do the rest.

Define

Extend the CalendarDefinition() class, implementing the following methods:

class calends.CalendarDefinition()

CalendarDefinition.name: The name of the calendar system. Can be static or set in the constructor().

CalendarDefinition.defaultFormat: The default/fallback format for the calendar system. Can be static or set in the constructor().

CalendarDefinition.constructor(): This can do anything you like.

CalendarDefinition.toInternal(stamp, format)

参数

stamp (any) – The input. Should support strings at the very minimum.
format (string) – The format string for parsing the input date.

返回

The parsed internal timestamp.

返回类型

TAI64Time()

抛出

CalendsException() – when an error occurs

Converts an input date/time representation to an internal TAI64Time().

CalendarDefinition.fromInternal(instant, format)

参数

instant (TAI64Time()) – The internal timestamp value.
format (string) – The format string for formatting the output date.

返回

The formatted date/time.

返回类型

string

抛出

CalendsException() – when an error occurs

Converts an internal TAI64Time() to a date/time string.

CalendarDefinition.offset(instant, offset)

参数

instant (TAI64Time()) – The internal timestamp value.
offset (any) – The input offset. Should support strings at the very minimum.

返回

The adjusted internal timestamp.

返回类型

TAI64Time()

抛出

CalendsException() – when an error occurs

Adds the given offset to an internal TAI64Time().

Registration

Register

Once it is registered with the library, your calendar system can be used from anywhere in your application. To register a system, simply call register() on an object of your new class:

CalendarDefinition.register(): Registers a calendar system instance with the internal Calends library.

Unregister

The way to unregister a calendar system is to do so manually, using the instance you created to register it with in the first place:

CalendarDefinition.unregister(): Removes a calendar system from the callback list.

Check and List

CalendarDefinition.isRegistered()

返回: Whether or not the calendar system is currently registered.
返回类型: bool

Returns whether or not a calendar system has been registered, yet.

CalendarDefinition.registered()

返回: The sorted list of calendar systems currently registered.
返回类型: [string]

Returns the list of calendar systems currently registered.

Types and Values

Now we get to the inner workings that make calendar systems function – even the built-in ones. The majority of the “magic” comes from the TAI64Time() object itself, as a reliable way of storing the exact instants being calculated, and the only way times are handled by the library itself. A handful of methods provide basic operations that calendar system developers can use to simplify their conversions (adding and subtracting the values of other timestamps, and importing/exporting timestamp values from/to string and numeric types, in particular), and a couple of helpers exclusively handle adding and removing UTC leap second offsets. As long as you can convert your dates to/from Unix timestamps in a string or numeric type, the rest is handled entirely by these helpers in the library itself.

class calends.TAI64Time()

TAI64Time() stores a TAI64NARUX instant in a reliable, easily-converted format. Each 9-digit fractional segment is stored in a separate 32-bit integer to preserve its value with a very high degree of accuracy, without having to rely on string parsing or external arbitrary-precision mathematics libraries.

TAI64Time.seconds: The number of TAI seconds since CE 1970-01-01 00:00:00 TAI. Should be an integer value.

备注

TAI vs UTC

You may have noticed that a TAI64Time object stores times in TAI seconds, not Unix seconds, with a timezone offset of TAI rather than UTC. This distinction is very important as it will affect internal calculations and comparisons to mix the two up. TAI time is very similar to Unix time (itself based on UTC time), with one major difference. While Unix/UTC seconds include the insertion and removal of “leap seconds” to keep the solar zenith at local noon (which is useful for day-to-day living and planning), TAI seconds are a continuous count, unconcerned with dates whatsoever. Indeed, the only reason a date was given in the description above was to make it easier for human readers to know exactly when 0 TAI took place.

In other words, once you have a Unix timestamp of your instant calculated, be sure to convert it using fromUTC() before returning the result to the rest of the library. And then, of course, you’ll also need to convert instants from the library back using toUTC() before generating outputs.

TAI64Time.nano: The first 9 digits of the timestamp’s fractional component.

TAI64Time.atto: The 10th through 18th digits of the fractional component.

TAI64Time.ronto: The 19th through 27th digits of the fractional component.

TAI64Time.udecto: The 28th through 36th digits of the fractional component.

TAI64Time.xindecto: The 37th through 45th digits of the fractional component.

TAI64Time.add(z)

参数

z (TAI64Time()) – The timestamp to add to the current one.

返回

The sum of the two timestamps.

返回类型

TAI64Time()

Calculates the sum of two TAI64Time() values.

TAI64Time.sub(z)

参数

z (TAI64Time()) – The timestamp to subtract from the current one.

返回

The difference of the two timestamps.

返回类型

TAI64Time()

Calculates the difference of two TAI64Time() values.

TAI64Time.toString()

返回: The decimal string representation of the current timestamp.
返回类型: string

Returns the decimal string representation of the TAI64Time() value.

TAI64Time.fromString(in)

参数

in (string) – The decimal string representation of a timestamp to calculate.

返回

The calculated timestamp.

返回类型

TAI64Time()

Calculates a TAI64Time() from its decimal string representation.

TAI64Time.toHex()

返回: The hexadecimal string representation of the current timestamp.
返回类型: string

Returns the hexadecimal string representation of the TAI64Time() value.

TAI64Time.fromHex(in)

参数

in (string) – The hexadecimal string representation of a timestamp to calculate.

返回

The calculated timestamp.

返回类型

TAI64Time()

Calculates a TAI64Time() from its hexadecimal string representation.

TAI64Time.toNumber()

返回: The numeric representation of the current timestamp.
返回类型: number

Returns the number representation of the TAI64Time() value.

TAI64Time.fromNumber(in)

参数

in (number) – The arbitrary-precision floating point representation of a timestamp to calculate.

返回

The calculated timestamp.

返回类型

TAI64Time()

Calculates a TAI64Time() from its numeric representation.

TAI64Time.fromUTC()

返回: The calculated timestamp.
返回类型: TAI64Time()

Removes the UTC leap second offset from a TAI64Time value.

TAI64Time.toUTC()

返回: The calculated timestamp.
返回类型: TAI64Time()

Adds the UTC leap second offset to a TAI64Time value.