vite-browserhash-repro

This repo demonstrates an issue affecting SvelteKit: sveltejs/kit#5952

Background

When SvelteKit server-renders a page, it includes a <script> tag that is effectively this:

<script type="module">
	import { start } from '/node_modules/@sveltejs/kit/src/runtime/client/start.js';
	// ...
</script>

This module, which is inside the @sveltejs/kit package but not exposed via pkg.exports, imports a module that is exposed via pkg.exports:

import { error } from '../../index/index.js';

If user code imports the same module...

import { error } from '@sveltejs/kit';

...then ideally it would resolve to the same module. Instead, the latter import gets a ?v=${browserHash} suffix:

/node_modules/@sveltejs/kit/src/runtime/index/index.js
/node_modules/@sveltejs/kit/src/runtime/index/index.js?v=xyz123

Because of that, the module is initialised twice, and instanceof checks fail.

Reproduction

This repro demonstrates the same thing happening in a much simpler form. After installing dependencies, run npm run dev and visit localhost:5173. The expectation is that the test module will be instantiated once, but it's instantiated twice — once from index.html...

<script type="module" src="/node_modules/test/index.js"></script>

...and once from src/index.js:

import 'test';