fix: set correct header for memory files

Author: underfin

packages/vite/src/node/server/environment.ts

@@ -13,11 +13,11 @@ import type {
 import { mergeConfig } from '../utils'
 import { fetchModule } from '../ssr/fetchModule'
 import type { DepsOptimizer } from '../optimizer'
-import { isDepOptimizationDisabled } from '../optimizer'
-import {
-  createDepsOptimizer,
-  createExplicitDepsOptimizer,
-} from '../optimizer/optimizer'
+// import { isDepOptimizationDisabled } from '../optimizer'
+// import {
+//   createDepsOptimizer,
+//   createExplicitDepsOptimizer,
+// } from '../optimizer/optimizer'
 import { resolveEnvironmentPlugins } from '../plugin'
 import { ERR_OUTDATED_OPTIMIZED_DEP } from '../../shared/constants'
 import { promiseWithResolvers } from '../../shared/utils'

packages/vite/src/node/server/middlewares/memoryFiles.ts

@@ -1,4 +1,5 @@
 import type { Connect } from 'dep-types/connect'
+import * as mrmime from 'mrmime'
 import { cleanUrl } from '../../../shared/utils'
 import type { ViteDevServer } from '..'
 
@@ -14,7 +15,13 @@ export function memoryFilesMiddleware(server: ViteDevServer, handleHtml: boolean
       ) {
         if (cleanedUrl.endsWith('.js')) {
           res.setHeader('Content-Type', 'text/javascript')
+        } else {
+          const mime = mrmime.lookup(cleanedUrl)
+          if (mime) {
+            res.setHeader('Content-Type', mime)
+          }
         }
+       
         const headers = server.config.server.headers
         if (headers) {
           for (const name in headers) {