Vite 8 / Rolldown

vite-env is compatible with Vite 8 and its Rolldown-based bundler. This page documents the specific implementation details that make it work correctly with Rolldown.

Minimum versions

Dependency	Minimum version
Vite	>= 8.0.0
Node.js	>= 20.19.0

moduleType: 'js'

Both buildClientModule() and buildServerModule() in virtual.ts return an object with a moduleType: 'js' property alongside the generated code:

return {
  moduleType: 'js', // Required: Vite 8 / Rolldown explicit moduleType
  code: `...`,
}

This tells Rolldown to treat the virtual module output as JavaScript. Without this property, Rolldown may not parse the module correctly and can fail to resolve imports from virtual:env/client or virtual:env/server.

Virtual module loading

The load() hook returns objects with both code and moduleType properties rather than a plain string. Returning a plain string was acceptable in Vite 5/6 with Rollup, but Rolldown-based Vite 8 expects the structured object format for virtual modules.

ESM-only

The plugin package uses "type": "module" in its package.json and is distributed exclusively as ESM. Vite 8 requires plugins to be ESM.

enforce: 'pre'

The plugin sets enforce: 'pre' in its plugin object. This means the plugin's hooks run before Vite's core transform hooks and before other plugins that do not set enforce. In practice this is important for the resolveId and load hooks, which must intercept virtual:env/client and virtual:env/server before any other plugin attempts to resolve them.

Leak detection in generateBundle

The generateBundle hook scans the output bundle for server-only variable values that may have been accidentally included in client-facing chunks. The bundle object is typed as read-only by Vite's plugin API, so vite-env casts it to Record<string, { type: string, code?: string }> and iterates its entries without modifying them. The hook short-circuits immediately when building in SSR mode (resolvedConfig.build.ssr), since server bundles are expected to contain server variables.

If a server-only variable value is found in a client chunk, the build is aborted with an error that names the variable and the chunk it was found in.