fix: js fallback sourcemap content should be using original content

[sapphi-red]

Description

Follow up to #14247.

fixes #14247 (comment)

I tested this change with VSCode, Chrome, Firefox.

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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[sapphi-red]

/ecosystem-ci run

[patak-dev]

Should this be () => string in case it doesn't end up being used to save the file read?

[sapphi-red]

send function is a sync function and is part of the public API. Therefore originalContent cannot be () => Promise<string>. To satisfy () => string, we need to change fsp.readFile to fs.readFileSync in getOriginalContent. But I guess async is better for perf.

[patak-dev]

It would be good to find a way to avoid the perf regression. In a full .ts code base, there will now be a new read for each transformed file that won't be used, no? I think at one point we could have an internal send function that is async (everywhere internal usage could be changed to await), but given that it may be complex, for now we could add a guard at https://github.com/vitejs/vite/pull/15135/files#diff-6d94d6934079a4f09596acc9d3f3d38ea426c6f8e98cd766567335d42679ca7cR208, with a comment? Even if it is redundant, we at least save a few reads?

[sapphi-red]

Ah, OK. I noticed I was missing type === 'js'.

[sapphi-red]

In a full .ts code base, there will now be a new read for each transformed file that won't be used, no?

Just to make it clear, this won't happen. .ts files will always have source maps, so map == null is always false.

[Soarex16]

Thank you for such a quick response!

I also checked in the WebStorm debugger and now everything works fine.

[vite-ecosystem-ci]

📝 Ran ecosystem CI on a8b6843: Open

suite	result	latest scheduled
analogjs	✅ success	✅ success
astro	✅ success	✅ success
histoire	❌ failure	❌ failure
ladle	✅ success	✅ success
laravel	❌ failure	❌ failure
marko	✅ success	✅ success
nuxt	❌ failure	❌ failure
nx	✅ success	✅ success
previewjs	✅ success	✅ success
qwik	✅ success	✅ success
rakkas	✅ success	✅ success
sveltekit	❌ failure	❌ failure
unocss	✅ success	✅ success
vike	✅ success	✅ success
vite-plugin-pwa	✅ success	✅ success
vite-plugin-react	✅ success	✅ success
vite-plugin-react-pages	✅ success	✅ success
vite-plugin-react-swc	✅ success	✅ success
vite-plugin-svelte	✅ success	✅ success
vite-plugin-vue	✅ success	✅ success
vite-setup-catalogue	✅ success	✅ success
vitepress	✅ success	✅ success
vitest	✅ success	✅ success