diff --git a/packages/vite/src/node/__tests__/scan.spec.ts b/packages/vite/src/node/__tests__/scan.spec.ts
index 28495709d02631..95f25c5a90db8e 100644
--- a/packages/vite/src/node/__tests__/scan.spec.ts
+++ b/packages/vite/src/node/__tests__/scan.spec.ts
@@ -1,4 +1,10 @@
-import { scriptRE, commentRE, importsRE } from '../optimizer/scan'
+import {
+  scriptRE,
+  commentRE,
+  importsRE,
+  multilineCommentsRE,
+  singlelineCommentsRE
+} from '../optimizer/scan'
 
 describe('optimizer-scan:script-test', () => {
   const scriptContent = `import { defineComponent } from 'vue'
@@ -102,4 +108,16 @@ describe('optimizer-scan:script-test', () => {
       expect(importsRE.test(str)).toBe(false)
     })
   })
+
+  test('script comments test', () => {
+    multilineCommentsRE.lastIndex = 0
+    let ret = `/*
+      export default { }
+      */`.replace(multilineCommentsRE, '')
+    expect(ret).not.toContain('export default')
+
+    singlelineCommentsRE.lastIndex = 0
+    ret = `//export default { }`.replace(singlelineCommentsRE, '')
+    expect(ret).not.toContain('export default')
+  })
 })
diff --git a/packages/vite/src/node/optimizer/scan.ts b/packages/vite/src/node/optimizer/scan.ts
index 26ad02675e518a..83eb9e703195ba 100644
--- a/packages/vite/src/node/optimizer/scan.ts
+++ b/packages/vite/src/node/optimizer/scan.ts
@@ -40,7 +40,8 @@ const htmlTypesRE = /\.(html|vue|svelte)$/
 export const importsRE =
   /(?<!\/\/.*)(?<=^|;|\*\/)\s*import(?!\s+type)(?:[\w*{}\n\r\t, ]+from\s*)?\s*("[^"]+"|'[^']+')\s*(?=$|;|\/\/|\/\*)/gm
 
-const multilineCommentsRE = /\/\*(.|[\r\n])*?\*\//gm
+export const multilineCommentsRE = /\/\*(.|[\r\n])*?\*\//gm
+export const singlelineCommentsRE = /\/\/.*/g
 
 export async function scanImports(config: ResolvedConfig): Promise<{
   deps: Record<string, string>
@@ -235,6 +236,10 @@ function esbuildScanPlugin(
               js += content + '\n'
             }
           }
+          // empty singleline & multiline comments to avoid matching comments
+          const code = js
+            .replace(multilineCommentsRE, '/* */')
+            .replace(singlelineCommentsRE, '')
 
           if (
             loader.startsWith('ts') &&
@@ -247,8 +252,6 @@ function esbuildScanPlugin(
             // the solution is to add `import 'x'` for every source to force
             // esbuild to keep crawling due to potential side effects.
             let m
-            // empty multiline comments to avoid matching commented out imports
-            const code = js.replace(multilineCommentsRE, '/* */')
             while ((m = importsRE.exec(code)) != null) {
               // This is necessary to avoid infinite loops with zero-width matches
               if (m.index === importsRE.lastIndex) {
@@ -258,11 +261,11 @@ function esbuildScanPlugin(
             }
           }
 
-          if (!js.includes(`export default`)) {
+          if (!code.includes(`export default`)) {
             js += `\nexport default {}`
           }
 
-          if (js.includes('import.meta.glob')) {
+          if (code.includes('import.meta.glob')) {
             return {
               // transformGlob already transforms to js
               loader: 'js',