From 93f3efa08a306099a3bb9cc81c8d7173fbbe1cae Mon Sep 17 00:00:00 2001
From: patak <matias.capeletto@gmail.com>
Date: Fri, 7 Apr 2023 17:21:23 +0200
Subject: [PATCH 1/2] fix: ignore sideEffects for scripts imported from html

---
 packages/vite/src/node/plugins/resolve.ts | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/packages/vite/src/node/plugins/resolve.ts b/packages/vite/src/node/plugins/resolve.ts
index 626b5909644700..7c1a8fcaade112 100644
--- a/packages/vite/src/node/plugins/resolve.ts
+++ b/packages/vite/src/node/plugins/resolve.ts
@@ -260,19 +260,24 @@ export function resolvePlugin(resolveOptions: InternalResolveOptions): Plugin {
         }
 
         if ((res = tryFsResolve(fsPath, options))) {
-          const resPkg = findNearestPackageData(
-            path.dirname(res),
-            options.packageCache,
-          )
           res = ensureVersionQuery(res, id, options, depsOptimizer)
           debug?.(`[relative] ${colors.cyan(id)} -> ${colors.dim(res)}`)
 
-          return resPkg
-            ? {
+          // If this isn't a script imported from a .html file, include side effects
+          // hints so the non-used code is properly tree-shaken during build time.
+          if (!importer?.endsWith('.html')) {
+            const resPkg = findNearestPackageData(
+              path.dirname(res),
+              options.packageCache,
+            )
+            if (resPkg) {
+              return {
                 id: res,
                 moduleSideEffects: resPkg.hasSideEffects(res),
               }
-            : res
+            }
+          }
+          return res
         }
       }
 

From 8ec9bb5a70ad67d39b1163c779e6a327d027e451 Mon Sep 17 00:00:00 2001
From: patak <matias.capeletto@gmail.com>
Date: Fri, 7 Apr 2023 19:25:49 +0200
Subject: [PATCH 2/2] test: add test for sideEffects false

---
 playground/html/__tests__/html.spec.ts      | 10 ++++++++++
 playground/html/side-effects/index.html     |  2 ++
 playground/html/side-effects/package.json   |  6 ++++++
 playground/html/side-effects/sideEffects.js |  1 +
 playground/html/vite.config.js              |  1 +
 5 files changed, 20 insertions(+)
 create mode 100644 playground/html/side-effects/index.html
 create mode 100644 playground/html/side-effects/package.json
 create mode 100644 playground/html/side-effects/sideEffects.js

diff --git a/playground/html/__tests__/html.spec.ts b/playground/html/__tests__/html.spec.ts
index 39294f5510aa17..144fcfe1d0003a 100644
--- a/playground/html/__tests__/html.spec.ts
+++ b/playground/html/__tests__/html.spec.ts
@@ -293,3 +293,13 @@ describe('importmap', () => {
     )
   })
 })
+
+describe('side-effects', () => {
+  beforeAll(async () => {
+    await page.goto(viteTestUrl + '/side-effects/')
+  })
+
+  test('console.log is not tree-shaken', async () => {
+    expect(browserLogs).toContain('message from sideEffects script')
+  })
+})
diff --git a/playground/html/side-effects/index.html b/playground/html/side-effects/index.html
new file mode 100644
index 00000000000000..cca7443bd8eedb
--- /dev/null
+++ b/playground/html/side-effects/index.html
@@ -0,0 +1,2 @@
+<h1>sideEffects false</h1>
+<script type="module" src="./sideEffects.js"></script>
diff --git a/playground/html/side-effects/package.json b/playground/html/side-effects/package.json
new file mode 100644
index 00000000000000..72a1449164f79b
--- /dev/null
+++ b/playground/html/side-effects/package.json
@@ -0,0 +1,6 @@
+{
+  "name": "@vitejs/test-html-side-effects",
+  "private": true,
+  "version": "0.0.0",
+  "sideEffects": false
+}
diff --git a/playground/html/side-effects/sideEffects.js b/playground/html/side-effects/sideEffects.js
new file mode 100644
index 00000000000000..6bfb77c68206c0
--- /dev/null
+++ b/playground/html/side-effects/sideEffects.js
@@ -0,0 +1 @@
+console.log('message from sideEffects script')
diff --git a/playground/html/vite.config.js b/playground/html/vite.config.js
index e6301ec5ebf4dd..c03421c16045b0 100644
--- a/playground/html/vite.config.js
+++ b/playground/html/vite.config.js
@@ -28,6 +28,7 @@ export default defineConfig({
         valid: resolve(__dirname, 'valid.html'),
         importmapOrder: resolve(__dirname, 'importmapOrder.html'),
         env: resolve(__dirname, 'env.html'),
+        sideEffects: resolve(__dirname, 'side-effects/index.html'),
       },
     },
   },