From 3e6b4e1f311b43aa1dc77d78150a601d9fe4b280 Mon Sep 17 00:00:00 2001
From: Jay <jasonsaayman@gmail.com>
Date: Thu, 7 May 2026 19:36:11 +0200
Subject: [PATCH] fix: error unexpected token in fetch JS compatibility issue
 with Webpack 4 (#10864)

* chore: added npm run lint step between install and build in build-and-run-vitest

* chore: acorn ^8.16.0 added as a devDependency

* test: added test to parse all lib files via acorn

* feat: added globalThis: "readonly"

* feat: ?? replaced with the verbose ternary
---
 .github/workflows/run-ci.yml    |  2 ++
 eslint.config.js                | 13 ++++++++++---
 lib/adapters/fetch.js           |  5 ++++-
 package-lock.json               |  1 +
 package.json                    |  1 +
 tests/unit/syntaxCompat.test.js | 30 ++++++++++++++++++++++++++++++
 6 files changed, 48 insertions(+), 4 deletions(-)
 create mode 100644 tests/unit/syntaxCompat.test.js

diff --git a/.github/workflows/run-ci.yml b/.github/workflows/run-ci.yml
index bc12947a..e514f192 100644
--- a/.github/workflows/run-ci.yml
+++ b/.github/workflows/run-ci.yml
@@ -27,6 +27,8 @@ jobs:
           cache: npm
       - name: Install dependencies
         run: npm ci --ignore-scripts
+      - name: Lint
+        run: npm run lint
       - name: Build project
         run: npm run build
       - name: Install Playwright with deps
diff --git a/eslint.config.js b/eslint.config.js
index 411e17c4..ce2b5e0e 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -33,20 +33,27 @@ export default [
     languageOptions: {
       globals: {
         ...globals.browser,
-        ...globals.node
+        ...globals.node,
+        globalThis: 'readonly'
       }
     }
   },
   {
     files: ['lib/adapters/http.js', 'lib/platform/node/**/*.js'],
     languageOptions: {
-      globals: globals.node
+      globals: {
+        ...globals.node,
+        globalThis: 'readonly'
+      }
     }
   },
   {
     files: ['lib/adapters/xhr.js', 'lib/platform/browser/**/*.js'],
     languageOptions: {
-      globals: globals.browser
+      globals: {
+        ...globals.browser,
+        globalThis: 'readonly'
+      }
     }
   }
 ];
diff --git a/lib/adapters/fetch.js b/lib/adapters/fetch.js
index e0b2600e..b9015a9b 100644
--- a/lib/adapters/fetch.js
+++ b/lib/adapters/fetch.js
@@ -28,7 +28,10 @@ const test = (fn, ...args) => {
 };
 
 const factory = (env) => {
-  const globalObject = utils.global ?? globalThis;
+  const globalObject =
+    utils.global !== undefined && utils.global !== null
+      ? utils.global
+      : globalThis;
   const { ReadableStream, TextEncoder } = globalObject;
 
   env = utils.merge.call(
diff --git a/package-lock.json b/package-lock.json
index bc85e2a4..fa34acba 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -29,6 +29,7 @@
         "@vitest/browser": "^4.1.5",
         "@vitest/browser-playwright": "^4.1.5",
         "abortcontroller-polyfill": "^1.7.8",
+        "acorn": "^8.16.0",
         "body-parser": "^2.2.2",
         "chalk": "^5.6.2",
         "cross-env": "^10.1.0",
diff --git a/package.json b/package.json
index 7a7a8c56..4b2204f2 100644
--- a/package.json
+++ b/package.json
@@ -141,6 +141,7 @@
     "@vitest/browser": "^4.1.5",
     "@vitest/browser-playwright": "^4.1.5",
     "abortcontroller-polyfill": "^1.7.8",
+    "acorn": "^8.16.0",
     "body-parser": "^2.2.2",
     "chalk": "^5.6.2",
     "cross-env": "^10.1.0",
diff --git a/tests/unit/syntaxCompat.test.js b/tests/unit/syntaxCompat.test.js
new file mode 100644
index 00000000..2b8e1766
--- /dev/null
+++ b/tests/unit/syntaxCompat.test.js
@@ -0,0 +1,30 @@
+import { describe, it, expect } from 'vitest';
+import { readFileSync, readdirSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { Parser } from 'acorn';
+
+const LIB_DIR = fileURLToPath(new URL('../../lib/', import.meta.url));
+const ECMA_VERSION = 2018;
+
+function walk(dir) {
+  const out = [];
+  for (const name of readdirSync(dir)) {
+    const full = join(dir, name);
+    if (statSync(full).isDirectory()) out.push(...walk(full));
+    else if (full.endsWith('.js')) out.push(full);
+  }
+  return out;
+}
+
+describe('lib/ source files parse as ES2018', () => {
+  for (const file of walk(LIB_DIR)) {
+    const rel = file.slice(LIB_DIR.length);
+    it(rel, () => {
+      const src = readFileSync(file, 'utf8');
+      expect(() =>
+        Parser.parse(src, { ecmaVersion: ECMA_VERSION, sourceType: 'module' })
+      ).not.toThrow();
+    });
+  }
+});