ES Temporal: 2 Minute Standards

You might have heard that Temporal has recently reached Stage 3 in ECMA, here's a #StandardsIn2Min explaination of it...

Since it's beginnings JavaScript has had only a rudimentary Date object. It copied Date from an early edition of Java and it was intended to be used for programming just about anything relating to time. While Java itself quickly deprecated and improved their situation, JavaScript implementations didn't follow suit. It also introduced its own warts and quirks to Date along the way. As a result, JavaScript libraries dedicated toward reasoning about the complexities of time, like moment.js became common and essential.

Temporal, now at stage 3 as of this writing, is the result of a lot of work initiated by maintainers of those projects and shepherded through the standards process. It introduces lots of rich APIs to the JavaScript standard library, hosted by a new top-level Temporal object. Large top-level introductions of this sort (like Temporal, Math and Intl) are exceedingly rare.

Temporal provides a number of objects, all immutable and serializable, and each with their own methods for reasoning about time in different ways.

It contains some fundamental concepts which implement standards for calendar systems and timezones respectively, and set the foundations for how a lot of methods do their work:

• Temporal.Calendar
• Temporal.TimeZone

It introduces Temporal.Instant which is used for dealing with an instant in time to various degrees of precision.

It also introduces a number of "plain" themed objects geared toward providing APIs for the different ways we think about time not simply in terms of different kinds of precision. For example...

• Temporal.PlainTime is for dealing with wall-clock time that is not associated with a particular date or time zone.
• Temporal.PlainMonthDay is for date without a year components, useful for annual events like "The fourth of July" or "Christmas Day".
• Temporal.PlainDateTime is for representing a calendar date and wall-clock time that does not carry time zone information, e.g. December 7th, 1995 at 3:00 PM (in the Gregorian calendar).
• Temporal.PlainYearMonth is useful for expressing things like "The October 2020 edition of Vanity Fair".

It also includes...

• Temporal.ZonedDateTime is for reasoning about dates and times in the timezone offsets reckoned by a particular calendar
• Temporal.Duration is used for measuring the duration between two temporal objects.
• Temporal.now provides APIs about current the moment in time.

You can learn a lot more by following through links in the Temporal proposal repo, including helpful Reference documentation and examples, a cookbook to help you get started and learn the ins and outs of Temporal which include a (not production ready) polyfill in every page so that you can open Dev Tools and explore for yourself.

If you're interested in hearing about the history, development, challenges, inner workings or rationale behind any of this, I recently hosted an edition of our podcast on this topic with guests who worked on the standard.