fix(html): move importmap before module scripts

[bluwy]

Description

fix #9334

Arrange script type="importmap" as first in transformIndexHtml.

Additional context

Needed this for dev external tests 🙂

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What is the purpose of this pull request?

• [x] Bug fix
• [ ] New Feature
• [ ] Documentation update
• [ ] Other

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• [x] Read the Contributing Guidelines.
• [x] Read the Pull Request Guidelines and follow the Commit Convention.
• [x] Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• [x] Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• [x] Ideally, include relevant tests that fail without this PR but pass with it.

[patak-dev]

Nice fix. I'm leaning towards the alternative proposal though. IIUC this PR could end up reordering styles and scrpts, no?

[bluwy]

This PR currently reorders script type-"module" only if an importmap exist, so other cases it should work like before. Also happy to try out the alternative though.

[sapphi-red]

I'm leaning towards the alternative one, too. I think it is more easy to understand the behavior, especially when an importmap is injected by transformIndexHtml.

Not sure if this would be surprising for users though.

I think a warning will make it less surprising. For example, when the input index.html has <script type="module"> before importmap.

[bluwy]

Updated to use a Vite plugin with transformIndexHtml to move the importmap instead. I didn't add a warning though as I think there are cases where someone has no control over where the importmap is injected in a Vite plugin (?).

Also avoiding traverseHtml to save a bit of perf.

[sapphi-red]

I didn't add a warning though as I think there are cases where someone has no control over where the importmap is injected in a Vite plugin (?).

I was thinking of when the input of transformIndexHtml is invalid, not during the transformIndexHtml. Example: https://stackblitz.com/edit/vitejs-vite-e3cqtr?file=index.html&terminal=dev This one is invalid and won't work before this PR but IIUC this works after this PR.

[bluwy]

Yeah I think that could be something that we can warn by default. Would have to warn before any transfromIndexHtml happens 🤔 I'll see if I can add that tomorrow.