MDN URL

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getTimeZones

What specific section or headline is this issue about?

Return value

What information was incorrect, unhelpful, or incomplete?

The Return value section states:

An array of strings representing supported time zones for the associated Locale, where each value is an IANA time zone canonical name, sorted in alphabetical order. If the locale identifier does not contain a region subtag, the returned value is undefined.

However, this is slightly inaccurate, as it may lead the developer into thinking it can bank on the fact this will only return IANA time zone value, which is not true. The LDML specifically states that, for consistency, it keeps time zones that have been removed by IANA.

CLDR contains locale data using a time zone ID from the tz database as the key, stability of the IDs is critical.

and

Not all TZDB links are in CLDR aliases. CLDR purposefully does not exactly match the Link structure in the TZDB.

See https://unicode.org/reports/tr35/#Time_Zone_Identifiers

What did you expect to see?

I would propose to change this to the following, with changes in emphasis:

An array of strings representing supported time zones for the associated Locale, where each value is an IANA time zone canonical name, sorted in alphabetical order. If the locale identifier does not contain a region subtag, the returned value is undefined. Keep in mind that the values do not necessarily match the IANA database that changes from time to time. The Unicode LDML keeps old time zones for stability purpose.

Do you have any supporting links, references, or citations?

LDML specifications section on time zone

Do you have anything more you want to share?

No response

MDN metadata