Ability to use local abbreviations (many users request it)

[ellenaua]

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I added ability to use local abbreviations. In 2017, IANA database deprecated these abbreviations but many users request it.

Usage example:

console.log(moment().tz('America/Sao_Paulo').format('HH:mm z'));  // 13:13 -03
 
moment.tz.useLocalAbbrs = true;
console.log(moment().tz('America/Sao_Paulo').format('HH:mm z'));   // 13:13 BRT

How it looks in packed.json:

"America/Sao_Paulo|LMT -03(BRT) -02(BRST)|36.s 30 20..."

@mj1856 what do you think about this? By default it will return -03 as it does now.

[gilmoreorless]

I know I'm not a maintainer, but I do follow the IANA updates closely. Personally, I don't think this is a good idea to implement, for a couple of reasons.

1. Correctness. The IANA database maintainers didn't just deprecate these specific abbreviations. They were removed entirely, because they had been completely made up by the maintainers and weren't official labels used by the relevant countries. Yes, they had been in use for a long time, and some of them had become common, but that doesn't stop them from being incorrect.
2. Maintenance. The JSON file containing the old abbreviations looks to be hand-coded, or generated by a script that isn't part of the PR. When (not if) the tzdb removes more abbreviations, how will that file be updated as part of the data update and release process?

I know some users are confused about why the abbreviations have been removed, but documentation and education can be provided. Given the maintenance-only status of this project, I think sticking as closely as possible to the correct IANA source data is more important.

Also, this PR is a bit confusing in its structure. There are 3 separate commits with identical messages, and a bunch of other completely unrelated commits relating to releases. That makes it much harder for reviewers to identify what the relevant changes are.

[mattjohnsonpint]

I tend to agree with Gilmore's points. Thanks for your efforts, but I recommend against this.

[ramseth001]

@ellenaua @mattjohnsonpint As a developer, I understand the valid points put forward by @gilmoreorless. But, where do we go from here ? How do we display the time of timezones which do not have abbreviations to people who do not understand the concept of IANA?

[ichernev]

@ramseth001 this question is more a matter of pleasing a particular set of users accustomed to a particular timezone abbreviation.

If you have a project that displays timestamps in different timezones and have people complain that they don't know what -03 means and want XYZ instead, just hardcode in your own code base that people in a particular zone prefer particular abbreviations. Just don't make this OUR job, because, as @gilmoreorless pointed out, it's not official and it's not correct.