fix: filter of BOM tags in json plugin (#8628)

packages/vite/src/node/plugins/importAnalysis.ts

@@ -36,6 +36,7 @@ import {
   normalizePath,
   prettifyUrl,
   removeImportQuery,
+  stripBomTag,
   timeFrom,
   transformResult,
   unwrapId
@@ -142,10 +143,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
       const start = performance.now()
       await init
       let imports: readonly ImportSpecifier[] = []
-      // strip UTF-8 BOM
-      if (source.charCodeAt(0) === 0xfeff) {
-        source = source.slice(1)
-      }
+      source = stripBomTag(source)
       try {
         imports = parseImports(source)[0]
       } catch (e: any) {

packages/vite/src/node/plugins/json.ts

@@ -9,6 +9,7 @@
 import { dataToEsm } from '@rollup/pluginutils'
 import { SPECIAL_QUERY_RE } from '../constants'
 import type { Plugin } from '../plugin'
+import { stripBomTag } from '../utils'
 
 export interface JsonOptions {
   /**
@@ -43,6 +44,8 @@ export function jsonPlugin(
       if (!jsonExtRE.test(id)) return null
       if (SPECIAL_QUERY_RE.test(id)) return null
 
+      json = stripBomTag(json)
+
       try {
         if (options.stringify) {
           if (isBuild) {

packages/vite/src/node/utils.ts

@@ -1014,3 +1014,12 @@ export function transformResult(
     map: needSourceMap ? s.generateMap({ hires: true, source: id }) : null
   }
 }
+
+// strip UTF-8 BOM
+export function stripBomTag(content: string): string {
+  if (content.charCodeAt(0) === 0xfeff) {
+    return content.slice(1)
+  }
+
+  return content
+}

playground/json/index.html

@@ -22,6 +22,9 @@
 <h2>JSON Module</h2>
 <pre class="module"></pre>
 
+<h2>Has BOM Tag</h2>
+<pre class="bom"></pre>
+
 <script type="module">
   import json, { hello } from './test.json'
   import deepJson, { name } from 'vue/package.json'
@@ -52,6 +55,9 @@
   import moduleJSON from 'json-module'
   text('.module', JSON.stringify(moduleJSON))
 
+  import hasBomJson from './json-bom/has-bom.json'
+  text('.bom', JSON.stringify(hasBomJson))
+
   function text(sel, text) {
     document.querySelector(sel).textContent = text
   }

playground/json/json-bom/has-bom.json

@@ -0,0 +1,4 @@
+{
+  "description": "This file is marked with BOM.",
+  "message": "If the parsing is successful, the BOM tag has been removed."
+}