feat(repo): Add ESLint rule to ban direct global. usage in shared package

.changeset/ripe-lamps-follow.md

@@ -0,0 +1,5 @@
+---
+"@clerk/shared": patch
+---
+
+Use `globalThis` instead of `global` in `isomorphicBtoa` and `isomorphicAtob` for cross-platform compatibility

eslint.config.mjs

@@ -89,6 +89,33 @@ const noNavigateUseClerk = {
   },
 };
 
+const noGlobalObject = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'Disallow direct usage of `global.` - use `globalThis` instead for cross-platform compatibility',
+      recommended: false,
+    },
+    messages: {
+      noGlobal:
+        'Use `globalThis` instead of `global` for cross-platform compatibility. The `global` object is Node.js-specific and may not exist in browser or other environments.',
+    },
+    schema: [],
+  },
+  create(context) {
+    return {
+      MemberExpression(node) {
+        if (node.object.type === 'Identifier' && node.object.name === 'global') {
+          context.report({
+            node,
+            messageId: 'noGlobal',
+          });
+        }
+      },
+    };
+  },
+};
+
 const noUnstableMethods = {
   meta: {
     type: 'problem',
@@ -219,6 +246,7 @@ export default tseslint.config([
     plugins: {
       'custom-rules': {
         rules: {
+          'no-global-object': noGlobalObject,
           'no-unstable-methods': noUnstableMethods,
         },
       },
@@ -442,6 +470,7 @@ export default tseslint.config([
     name: 'packages/shared',
     files: ['packages/shared/src/**/*'],
     rules: {
+      'custom-rules/no-global-object': 'error',
       'no-restricted-imports': [
         'error',
         {
@@ -461,6 +490,14 @@ export default tseslint.config([
       ],
     },
   },
+  {
+    name: 'packages/shared - tests',
+    files: ['packages/shared/src/**/__tests__/**/*', 'packages/shared/src/**/*.test.{ts,tsx}'],
+    rules: {
+      // Allow `global.` in test files for mocking (e.g., global.window, global.console)
+      'custom-rules/no-global-object': 'off',
+    },
+  },
   {
     name: 'packages/expo-passkeys',
     files: ['packages/expo-passkeys/src/**/*'],

packages/shared/src/isomorphicAtob.ts

@@ -1,12 +1,12 @@
 /**
  * A function that decodes a string of data which has been encoded using base-64 encoding.
- * Uses `atob` if available, otherwise uses `Buffer` from `global`. If neither are available, returns the data as-is.
+ * Uses `atob` if available, otherwise uses `Buffer` from `globalThis`. If neither are available, returns the data as-is.
  */
 export const isomorphicAtob = (data: string) => {
   if (typeof atob !== 'undefined' && typeof atob === 'function') {
     return atob(data);
-  } else if (typeof global !== 'undefined' && global.Buffer) {
-    return new global.Buffer(data, 'base64').toString();
+  } else if (typeof globalThis.Buffer !== 'undefined') {
+    return globalThis.Buffer.from(data, 'base64').toString();
   }
   return data;
 };

packages/shared/src/isomorphicBtoa.ts

@@ -1,8 +1,8 @@
 export const isomorphicBtoa = (data: string) => {
   if (typeof btoa !== 'undefined' && typeof btoa === 'function') {
     return btoa(data);
-  } else if (typeof global !== 'undefined' && global.Buffer) {
-    return new global.Buffer(data).toString('base64');
+  } else if (typeof globalThis.Buffer !== 'undefined') {
+    return globalThis.Buffer.from(data).toString('base64');
   }
   return data;
 };