fix: HEAD request Content-Type for JS files in transform middleware

.github/copilot-instructions.md

@@ -0,0 +1,29 @@
+This is a TypeScript project that implements a frontend build tooling called Vite. Please follow these guidelines when contributing:
+
+## Code Standards
+
+### Required Before Each Commit
+
+- Run `pnpm run lint` to ensure that your code adheres the code standards.
+- Run `pnpm run format` to format your code.
+
+### Development Flow
+
+- Build: `pnpm run build`
+- Test: `pnpm run test` (uses Vitest and Playwright)
+
+## Repository Structure
+
+- `docs/`: Documentation.
+- `packages/create-vite`: Contains the source code for the `create-vite` command.
+- `packages/plugin-legacy`: Contains the source code for `@vitejs/plugin-legacy`.
+- `packages/vite`: Contains the source code for the Vite core.
+- `playground/`: E2E tests
+
+## Key Guidelines
+
+1. Follow TypeScript best practices.
+2. Maintain existing code structure and organization.
+3. Write tests for new functionality. Prefer uni tests if it can be tested without using mocks.
+4. Never write comments that explain what the code does. Instead, write comments that explain why the code does what it does.
+5. Suggest changes to the documentation if public API changes are made.

.github/workflows/copilot-setup-steps.yml

@@ -0,0 +1,47 @@
+on:
+  workflow_dispatch:
+  push:
+    paths:
+      - .github/workflows/copilot-setup-steps.yml
+  pull_request:
+    paths:
+      - .github/workflows/copilot-setup-steps.yml
+
+jobs:
+  copilot-setup-steps:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@a7487c7e89a18df4991f7f222e4898a00d66ddda # v4.1.0
+
+      - name: Set node version to 22
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: "pnpm"
+
+      - name: Install deps
+        run: pnpm install
+
+      # Install playwright's binary under custom directory to cache
+      - name: (non-windows) Set Playwright path and Get playwright version
+        if: runner.os != 'Windows'
+        run: |
+          echo "PLAYWRIGHT_BROWSERS_PATH=$HOME/.cache/playwright-bin" >> $GITHUB_ENV
+          PLAYWRIGHT_VERSION="$(pnpm ls --depth 0 --json -w playwright-chromium | jq --raw-output '.[0].devDependencies["playwright-chromium"].version')"
+          echo "PLAYWRIGHT_VERSION=$PLAYWRIGHT_VERSION" >> $GITHUB_ENV
+      - name: (windows) Set Playwright path and Get playwright version
+        if: runner.os == 'Windows'
+        run: |
+          echo "PLAYWRIGHT_BROWSERS_PATH=$HOME\.cache\playwright-bin" >> $env:GITHUB_ENV
+          $env:PLAYWRIGHT_VERSION="$(pnpm ls --depth 0 --json -w playwright-chromium | jq --raw-output '.[0].devDependencies["playwright-chromium"].version')"
+          echo "PLAYWRIGHT_VERSION=$env:PLAYWRIGHT_VERSION" >> $env:GITHUB_ENV
+
+      - name: Install Playwright
+        # does not need to explicitly set chromium after https://github.com/microsoft/playwright/issues/14862 is solved
+        run: pnpm playwright install chromium

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

@@ -124,7 +124,10 @@ export function transformMiddleware(
   return async function viteTransformMiddleware(req, res, next) {
     const environment = server.environments.client
 
-    if (req.method !== 'GET' || knownIgnoreList.has(req.url!)) {
+    if (
+      (req.method !== 'GET' && req.method !== 'HEAD') ||
+      knownIgnoreList.has(req.url!)
+    ) {
       return next()
     }
 

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

@@ -92,6 +92,10 @@ export function send(
   }
 
   res.statusCode = 200
-  res.end(content)
+  if (req.method === 'HEAD') {
+    res.end()
+  } else {
+    res.end(content)
+  }
   return
 }

playground/resolve/__tests__/resolve.spec.ts

@@ -1,8 +1,8 @@
 import fs from 'node:fs'
 import path from 'node:path'
 import { fileURLToPath } from 'node:url'
-import { expect, test } from 'vitest'
-import { isBuild, isWindows, page, testDir, viteTestUrl } from '~utils'
+import { describe, expect, test } from 'vitest'
+import { isBuild, isServe, isWindows, page, testDir, viteTestUrl } from '~utils'
 
 test('bom import', async () => {
   expect(await page.textContent('.utf8-bom')).toMatch('[success]')
@@ -263,3 +263,25 @@ test.runIf(isBuild)('sideEffects field glob pattern is respected', async () => {
   )
   expect(sideEffectValues).toStrictEqual(['success'])
 })
+
+describe.runIf(isServe)('HEAD request handling', () => {
+  test('HEAD request to JS file returns correct Content-Type', async () => {
+    const response = await fetch(new URL('/absolute.js', viteTestUrl), {
+      method: 'HEAD',
+    })
+    expect(response.headers.get('content-type')).toBe('text/javascript')
+    expect(response.status).toBe(200)
+    const text = await response.text()
+    expect(text).toBe('')
+  })
+  test('HEAD request to CSS file returns correct Content-Type', async () => {
+    const response = await fetch(new URL('/style.css', viteTestUrl), {
+      method: 'HEAD',
+      headers: {
+        Accept: 'text/css',
+      },
+    })
+    expect(response.headers.get('content-type')).toBe('text/css')
+    expect(response.status).toBe(200)
+  })
+})

playground/resolve/style.css

@@ -0,0 +1,5 @@
+/* Simple CSS for HEAD request testing */
+body {
+  margin: 0;
+  padding: 0;
+}