javascriptdatetimelocalizationtimezoneecmascript-intl

Intl.DateTimeFormat: Why is timeZoneName: "shortOffset" is having a different value in different languages

We are currently exploring showing timestamps with time zone to our users and decided to go with the Intl.DateTimeFormat option timeZoneName: "shortOffset" but we now noticed that the value is different between the languages.

When I run this snippet in chrome printing the timezone in different languages:

["it-IT", "da-DK", "de-DE", "en-GB", "es-ES", "pl-PL", "fr-FR", "sv-SE", "nl-NL", "nb-NO", "el-GR", "fi-FI", "pt-PT", "cs-CZ", ].forEach((l) => {
  const tz = Intl.DateTimeFormat(l, {
      timeZone: "Asia/Kolkata",
      timeZoneName: "shortOffset",
    })
    .formatToParts(new Date())
    .find((p) => p.type === "timeZoneName").value;

  console.log(l, tz);
});

I get this result:

language timezone
it-IT GMT+5:30
da-DK GMT+5.30
de-DE GMT+5:30
en-GB GMT+5:30
es-ES GMT+5:30
pl-PL GMT+5:30
fr-FR UTC+5:30
sv-SE GMT+5:30
nl-NL GMT+5:30
nb-NO GMT+5:30
el-GR GMT+5:30
fi-FI UTC+5.30
pt-PT GMT+5:30
cs-CZ GMT+5:30

so for some reason french and finnish are using the label UTC and all the other tested languages are using GMT.

I would really like to know what the reason behind this is. Is there any documentation or database where I can find the configuration of the different languages for Intl.DateTimeFormat?

Solution

  • A few things: