Update all packages to use createConfig

eslint.config.mjs

@@ -1,13 +1,11 @@
 // @ts-check
 
-import base from '@metamask/eslint-config';
+import base, { createConfig } from '@metamask/eslint-config';
 import nodejs from '@metamask/eslint-config-nodejs';
 import typescript from '@metamask/eslint-config-typescript';
 import vitest from '@metamask/eslint-config-vitest';
-// eslint-disable-next-line import-x/no-unresolved
-import tseslint from 'typescript-eslint';
 
-const config = tseslint.config(
+const config = createConfig([
   {
     ignores: ['.yarn/'],
   },
@@ -58,6 +56,6 @@ const config = tseslint.config(
       'n/no-unpublished-require': 'off',
     },
   },
-);
+]);
 
 export default config;

packages/base/README.md

@@ -24,17 +24,17 @@ with `@metamask/eslint-config` first, and `@metamask/eslint-config-*` in any
 order thereafter.
 
 ```js
-import base from '@metamask/eslint-config';
-
-const config = {
-  // Any custom shared config should be added here.
-  // ...
-
-  // This should be added last unless you know what you're doing.
-  ...base,
+import base, { createConfig } from '@metamask/eslint-config';
 
+const config = createConfig({
   {
-    // Your overrides here.
+    extends: [
+      // Any custom shared config should be added here.
+      // ...
+
+      // This should be added last unless you know what you're doing.
+      base,
+    ],
   }
-};
+});
 ```

packages/base/src/index.d.mts

@@ -1,6 +1,64 @@
 declare module '@metamask/eslint-config' {
   import type { Linter } from 'eslint';
 
-  const config: Linter.Config[];
+  /**
+   * An ESLint configuration object.
+   */
+  type Config = Linter.Config;
+
+  /**
+   * An ESLint configuration object that may extend other configurations. This
+   * can only be used with the {@link createConfig} function.
+   */
+  type ConfigWithExtends = Config & {
+    extends?: Config | Config[] | Config[][];
+  };
+
+  /**
+   * Create a config object that extends other configs.
+   *
+   * ESLint 9 removed support for extending arrays of configs, so this function
+   * provides a workaround. It takes an array of config objects, where each object
+   * may have an `extends` property that is an array of other config objects.
+   *
+   * This function is inspired by the `config` function in the `typescript-eslint`
+   * package, but to avoid a dependency on that package, this function is
+   * implemented here.
+   *
+   * @param configs - An array of config objects.
+   * @returns An array of config objects with all `extends` properties
+   * resolved.
+   * @example Basic usage.
+   * import { createConfig } from '@metamask/eslint-config';
+   * import typescript from '@metamask/eslint-config-typescript';
+   *
+   * const configs = createConfig([
+   *   {
+   *     files: ['**\/*.ts'],
+   *     extends: typescript,
+   *   },
+   * ]);
+   *
+   * export default configs;
+   *
+   * @example Multiple extends are supported as well.
+   * import { createConfig } from '@metamask/eslint-config';
+   * import typescript from '@metamask/eslint-config-typescript';
+   * import nodejs from '@metamask/eslint-config-nodejs';
+   *
+   * const configs = createConfig([
+   *   {
+   *     files: ['**\/*.ts'],
+   *     extends: [typescript, nodejs],
+   *   },
+   * ]);
+   *
+   * export default configs;
+   */
+  export function createConfig(
+    configs: ConfigWithExtends | ConfigWithExtends[],
+  ): Config[];
+
+  const config: Config[];
   export default config;
 }

packages/browser/README.md

@@ -25,18 +25,19 @@ with `@metamask/eslint-config` first, and `@metamask/eslint-config-*` in any
 order thereafter.
 
 ```js
-import base from '@metamask/eslint-config';
+import base, { createConfig } from '@metamask/eslint-config';
 import browser from '@metamask/eslint-config-browser';
 
-const config = {
-  // Any custom shared config should be added here.
-  // ...
-
-  // This should be added last unless you know what you're doing.
-  ...base,
-  ...browser,
+const config = createConfig({
   {
-    // Your overrides here.
+    extends: [
+      // Any custom shared config should be added here.
+      // ...
+
+      // This should be added last unless you know what you're doing.
+      base,
+      browser,
+    ],
   }
-};
+});
 ```

packages/browser/src/index.mjs

@@ -1,3 +1,4 @@
+import { createConfig } from '@metamask/eslint-config';
 import globals from 'globals';
 import { createRequire } from 'module';
 
@@ -8,33 +9,18 @@ const environmentRules = customRequire('./environment.json');
 /**
  * @type {import('eslint').Linter.Config[]}
  */
-const config = [
-  {
-    name: '@metamask/eslint-config-browser',
+const config = createConfig({
+  name: '@metamask/eslint-config-browser',
 
-    files: [
-      '**/*.js',
-      '**/*.jsx',
-      '**/*.mjs',
-      '**/*.cjs',
-      '**/*.ts',
-      '**/*.tsx',
-      '**/*.mts',
-      '**/*.cts',
-      '**/*.mtsx',
-      '**/*.ctsx',
-    ],
-
-    languageOptions: {
-      globals: {
-        ...globals.browser,
-      },
+  languageOptions: {
+    globals: {
+      ...globals.browser,
     },
+  },
 
-    rules: {
-      ...environmentRules,
-    },
+  rules: {
+    ...environmentRules,
   },
-];
+});
 
 export default config;

packages/commonjs/README.md

@@ -23,19 +23,19 @@ with `@metamask/eslint-config` first, and `@metamask/eslint-config-*` in any
 order thereafter.
 
 ```js
-import base from '@metamask/eslint-config';
+import base, { createConfig } from '@metamask/eslint-config';
 import commonjs from '@metamask/eslint-config-commonjs';
 
-const config = {
-  // Any custom shared config should be added here.
-  // ...
-
-  // This should be added last unless you know what you're doing.
-  ...base,
-  ...commonjs,
-
+const config = createConfig({
   {
-    // Your overrides here.
+    extends: [
+      // Any custom shared config should be added here.
+      // ...
+
+      // This should be added last unless you know what you're doing.
+      base,
+      commonjs,
+    ],
   }
-};
+});
 ```

packages/commonjs/src/index.mjs

@@ -1,3 +1,4 @@
+import { createConfig } from '@metamask/eslint-config';
 import globals from 'globals';
 import { createRequire } from 'module';
 
@@ -8,33 +9,18 @@ const environmentRules = customRequire('./environment.json');
 /**
  * @type {import('eslint').Linter.Config[]}
  */
-const config = [
-  {
-    name: '@metamask/eslint-config-commonjs',
+const config = createConfig({
+  name: '@metamask/eslint-config-commonjs',
 
-    files: [
-      '**/*.js',
-      '**/*.jsx',
-      '**/*.mjs',
-      '**/*.cjs',
-      '**/*.ts',
-      '**/*.tsx',
-      '**/*.mts',
-      '**/*.cts',
-      '**/*.mtsx',
-      '**/*.ctsx',
-    ],
-
-    languageOptions: {
-      globals: {
-        ...globals.commonjs,
-      },
+  languageOptions: {
+    globals: {
+      ...globals.commonjs,
     },
+  },
 
-    rules: {
-      ...environmentRules,
-    },
+  rules: {
+    ...environmentRules,
   },
-];
+});
 
 export default config;

packages/jest/README.md

@@ -24,19 +24,19 @@ with `@metamask/eslint-config` first, and `@metamask/eslint-config-*` in any
 order thereafter.
 
 ```js
-import base from '@metamask/eslint-config';
-import commonjs from '@metamask/eslint-config-commonjs';
-
-const config = {
-  // Any custom shared config should be added here.
-  // ...
-
-  // This should be added last unless you know what you're doing.
-  ...base,
-  ...commonjs,
+import base, { createConfig } from '@metamask/eslint-config';
+import jest from '@metamask/eslint-config-jest';
 
+const config = createConfig({
   {
-    // Your overrides here.
+    extends: [
+      // Any custom shared config should be added here.
+      // ...
+
+      // This should be added last unless you know what you're doing.
+      base,
+      jest,
+    ],
   }
-};
+});
 ```