feat(server): file request response content type contains utf-8

[btea]

Description

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[bluwy]

There's some discussion about this at #14142 (comment). I'm still open to this possibility, but I'm not sure if it's entirely safe for dev to assume utf-8 always.

[btea]

When I opened the project using Edge, I encountered the following warning message, so I created this PR.

[sapphi-red]

It seems the warning is not shown if it's localhost. That's why I didn't find it in past.

I wonder if it's better to leave it so that users would add <meta charset="utf-8"> in case the server is not configured to send the charset.

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While I think we can add it to HTML, I think it's incorrect to set charset=utf-8 to binary files. Also I think we don't need to add to JS files and JSON files.

• Binary files (e.g. .png) are not text and doesn't make sense to add charset.
• For JS files, ESM files must be encoded as UTF-8 and is always processed as UTF-8.
• JSON files needs to be UTF-8 per spec and charset is not defined for JSON mime.

I'm not sure about CSS files. If we set it, it will override the @charset value.
https://developer.mozilla.org/en-US/docs/Web/CSS/@charset#:~:text=The%20value%20of,is%20UTF%2D8
Vite assumes the file to be encoded as UTF-8, but raw files (e.g. files in public) can use other encodings.

[bluwy]

Also since #14756, charset=utf-8 is not set for HTML by default in preview. Dev also doesn't set it as before. I think it's fair for users to use <meta charset="utf-8"> manually, or add a middleware that auto-sets it.

[btea]

@bluwy @sapphi-red Thank you for your detailed comments. According to the For JS files, ESM files must be encoded as UTF-8 and is always processed as UTF-8 mentioned by @sapphi-red , so maybe I just need to add chartset=utf-8 here to determine whether it is a js file?

[bluwy]

I still don't quite see why Edge is flagging this an issue. From what I understand, we don't have to set charset=utf8 for JS, that's only a recommendation.

The screenshot links to these:

• https://webhint.io/docs/user-guide/hints/hint-content-type/
• https://webhint.io/docs/user-guide/hints/hint-meta-charset-utf-8/

And it doesn't provide a strong reason for JS files.

[sapphi-red]

No, that would set charset=utf-8 to classic scripts as well. (classic scripts doesn't need to be UTF-8.)
ESM files will always be processed as UTF-8 so there's no reason to specify by the mime type.

[btea]

Thank you for your detailed reply. Based on your views, we should maintain the status quo and I will close this PR.