Experiment: Remember language 🧪

[caugner]

tl;dr

We launched an experimental MDN feature on September 25, 2024 that allows users to choose their preferred language and automatically switch to this language when the requested content is available in that language.

Background

MDN is currently available in English (en-US) and 8 other translated languages (es, fr, ja, ko, pt-BR, ru, zh-CN, zh-TW) and users have always been able to switch to their preferred language manually using the language menu.

Problem

There have been two outstanding issues:

1. Some users prefer English, but their search engine suggests links to their local or native language, so every time these users have to manually switch to their preferred language.
2. Some users prefer a translated language and some content is unavailable in these languages, so MDN links to the English language instead, but this means these users have to manually switch back to their preferred language.

Solution

We have introduced a "Remember language" setting in the language menu. Enabling the setting saves the current language in the preferredlocale cookie, and this will prompt MDN to redirect users whenever they navigate to a page that is available in that language. Disabling the setting will delete the cookie, and users will no longer be redirected.

Note: The cookie has been previously used to save the last language that the user switched to. For this reason, the setting is enabled for all users that have recently switched the language on MDN.

Use case 1: Preference for English

Charlie lives in France and uses French Google, but prefers to read MDN in English, so they enabled "Remember language" while browsing MDN in English.

• Charlie searches for "localstorage" on Google.
• Google suggests https://developer.mozilla.org/fr/docs/Web/API/Window/localStorage in French.
• Charlie clicks on the link.
• Because Charlie's browser sends the preferredlocale=en-US cookie, they now get redirected to English:

  /fr/docs/Web/API/Window/localStorage
  → /en-US/docs/Web/API/Window/localStorage
  

• Charlie no longer has to switch the language manually.

Use case 2: Preference for translated language

Jin lives in South Korea and has basic English knowledge, but prefers to read MDN in Korean, their native language, so they enabled "Remember language" while browsing MDN in Korean.

• Jin is browsing MDN in Korean, and clicks on Blog in the top menu.
• As the Blog is only available in English, Jin is now browsing MDN in English.
• Jin opens the "New JavaScript set methods" blog post.
• The Blog post contains links to several English pages in the MDN Web Docs, like the following one:

  intersection() returns a new set with elements in both this set and the given set.

• Jin clicks on the intersection() link.
• Because Jin's browser sends the preferredlocale=ko cookie and the page is available in Korean, they now get redirected to:

  /en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/intersection
  → /ko/docs/Web/JavaScript/Reference/Global_Objects/Set/intersection
  

• Jin no longer has to switch the language manually.

[pransh15]

This is an amazing experiment, I'd love to hear how it ends up helping folks read better on MDN! 📚

[nicbou]

I have just found this page from the "?" icon next to the feature. I just wanted to sing a few words of praise.

A bit of feedback:

• I speak French, English and German, in order of fluency
• My browser languages are German, English and French, in order of preference
• I prefer to read documentation in English, the technical language I prefer
• Google prefers to show me results in German, as I intend it

So what is my intent? It depends on the task:

• German to get a bit of language practice
• English because it's the language I usually work in
• English because the original is often much better than the translation
• French/German because the task has some cultural context
• English/French/German because I need instructions in the same language as the software or operating system I am using

A pet peeve of mine is clicking on an English result and seeing the German version, then having to scroll all the way to the bottom of the page to change the language. A bit later, I click another English result and the same thing happens again.

I find your approach very elegant, and accommodating to all user intents. Very well done!

[pthebaul]

I was wondering why my automatic redirection to English was acting weird, turns out I don't need it anymore!

Thank you for this QoL experiment!

[StomperHK]

OMG YOU ARE A SAVIOUR. For years I had to manually change the langague to english, because MDN translations are inconsistent (they generally have less content that the page in english and some layouts are broken).

[decrecementofeliz]

Hi!

Some weird behaviour regarding language redirections: If a MDN url is shared with NO language slug (without the /en-US/ or any other language part), it will redirect to the 'remember language' locale version of that page regardless if that translation exists or not.

Example:

• This page has no Spanish translation: https://developer.mozilla.org/en-US/docs/Web/CSS/@page/size
• I've chosen Spanish in the Remember language setting

In this scenario:

• https://developer.mozilla.org/en-US/docs/Web/CSS/@page/size shows the English fallback page as expected, no redirects, OK
• https://developer.mozilla.org/docs/Web/CSS/@page/size redirects 302 to https://developer.mozilla.org/es/docs/Web/CSS/@page/size, where I see a Page not found message with a link to the English page.

Maybe this extra click to get to the English fallback page is the intended way to work. But it's a bit weird given that MDN asks to always use this non-localized format in the "mdn_url" field of several repos and services like BCD.

One idea: all these non-localized urls could always be redirected to the /en-US/ version in the first place; then, if the user has set a preferred language, check if that page has a locale version. If the translation exists, redirect, and if not, stays on the English page.

Not sure if this is a good idea as it could generate a lot of redirects. Another option would be to change all those mdn_urls to their /en-US/ version in the origin, but I guess that would also involve other complex things beyond my experience. And having that extra click is not a big deal for the user, really. Anyway, I came upon all these links and just wanted to point that out.

Regards!

[caugner]

Thank you for taking the time to report this issue, which is similar to mdn/yari#11717.

@decrecementofeliz Can you share whether your browser's preferred languages include English? You can check via this Playground.

[decrecementofeliz]

Hi, yes, my browser (Firefox) includes English (and Galician and Spanish) as preferred language:

en,gl,es