feat: initial support for Temporal equality

[dirkluijk]

Description

Fixes #7991

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[hi-ogawa]

Do you know which is preferred whether toString equality and builtin equals method? https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Temporal/ZonedDateTime/equals

It looks like there are several old issues mentions calendar comparison (such as tc39/proposal-temporal#625), but the discussion seem quite technical 😅

[dirkluijk]

.equals() seems to compare including the calendar, so I think it's a good suggestion. Let's do it!

For Temporal.Duration this .equals() method doesn't exist, but I wasn't sure about that one to begin with. For Durations, there IS actually ambiguity. For example, are 60 seconds and 1 minute the same? If you compare the duration in time, yes; but if you literally compare all their components, no. Also, for example "1 day" is not necessarily the same as "24 hour" and depends on context.

My suggestion is to use .toString() for durations so it does a literal comparison of all the different components.

[hi-ogawa]

Indeed it looks like Duration is tricky. tc39/proposal-temporal#856 seems to explain the details.

As a builtin equality, I think choosing toString comparison makes sense since that's the most strict way to do it. Users can still add own custom equality tester to loosen it if desired.

[dirkluijk]

@hi-ogawa I updated the PR:

• added Temporal polyfill
• adjusted equality check and use .equals()
• for Duration I still compare the string representation to compare all its components.

[hi-ogawa]

Thanks!