Browser language lookup is incorrectly using ISO 639-1 instead of BCP 47

[tfmorris]

Problem

As I mentioned in #5997 (comment), the language tags sent by browsers are based on BCP 47, not ISO 639-1, so doing ISO 639-1 based lookups is incorrect. This will not work for the over 300 MARC languages which don't have ISO 639-1 codes, disenfranchising those users.

In Wikidata, these can be found using the property P305 "IETF Language Tag". For languages which have ISO 639-1 codes, these will overlap, but most languages do not have an ISO 639-1 code.

Reproducing the bug

• Expected behavior: Language specific searches like Random Book work for all MARC languages
• Actual behavior: Only ISO 639-1 languages work

Context

• Browser (Chrome, Safari, Firefox, etc):
• OS (Windows, Mac, etc):
• Logged in (Y/N):
• Environment (prod, dev, local): prod

Breakdown

Implementation Details (for maintainers)

Requirements Checklist

• [ ]

Related files

Stakeholders

• @cdrini
• @mekarpeles

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[vijayalakshmipokala]

Hi @tfmorris ,

I'm interested in working on this issue.

Could you please point me to the part of the codebase where the browser language lookup is currently implemented? I would like to understand how ISO 639-1 is currently being used before attempting to add support for BCP 47 language tags.

Also, since this issue has the "Needs: Breakdown" label, are there any specific subtasks contributors could help with?

Thank you!