Upgrade eslint to v9 with newer recommended configs

.prettierrc

@@ -4,7 +4,7 @@
   "semi": true,
   "tabWidth": 2,
   "printWidth": 100,
-  "importOrder": ["<THIRD_PARTY_MODULES>", "^[./]"],
+  "importOrder": ["<THIRD_PARTY_TS_TYPES>", "^[./]"],
   "importOrderSeparation": false,
   "importOrderSortSpecifiers": true,
   "importOrderParserPlugins": ["typescript"],

eslint.config.dist.mjs

@@ -0,0 +1,12 @@
+// @ts-check
+import compat from 'eslint-plugin-compat';
+
+const compatPlugin = compat.configs['flat/recommended'];
+
+compatPlugin.settings = { ...compatPlugin.settings, lintAllEsApis: true };
+
+if (compatPlugin.rules) {
+  compatPlugin.rules['compat/compat'] = 'warn'; // TODO once we've updated browser support and use feature detection that this plugin can understand we can change this to 'error'
+}
+
+export default [compatPlugin];

eslint.config.mjs

@@ -0,0 +1,171 @@
+// @ts-check
+import js from '@eslint/js';
+import { configs, plugins, rules } from 'eslint-config-airbnb-extended';
+import { rules as prettierConfigRules } from 'eslint-config-prettier';
+import prettierPlugin from 'eslint-plugin-prettier';
+
+const strictness = 'off';
+
+const jsConfig = [
+  // ESLint Recommended Rules
+  {
+    name: 'js/config',
+    ...js.configs.recommended,
+  },
+  // Stylistic Plugin
+  plugins.stylistic,
+  // Import X Plugin
+  plugins.importX,
+  // Airbnb Base Recommended Config
+  ...configs.base.recommended,
+  // Strict Import Config
+  rules.base.importsStrict,
+];
+
+const typescriptConfig = [
+  // TypeScript ESLint Plugin
+  plugins.typescriptEslint,
+  // Airbnb Base TypeScript Config
+  ...configs.base.typescript,
+  // Strict TypeScript Config
+  rules.typescript.typescriptEslintStrict,
+];
+
+const prettierConfig = [
+  // Prettier Plugin
+  {
+    name: 'prettier/plugin/config',
+    plugins: {
+      prettier: prettierPlugin,
+    },
+  },
+  // Prettier Config
+  {
+    name: 'prettier/config',
+    rules: {
+      ...prettierConfigRules,
+      'prettier/prettier': 'error',
+    },
+  },
+];
+
+export default [
+  // Javascript Config
+  ...jsConfig,
+  // TypeScript Config
+  ...typescriptConfig,
+  // Prettier Config
+  ...prettierConfig,
+  {
+    languageOptions: {
+      parserOptions: {
+        projectService: false,
+        project: './tsconfig.eslint.json',
+      },
+    },
+    rules: {
+      'import/export': 'off',
+      'max-classes-per-file': 'off',
+      'no-param-reassign': 'off',
+      'no-await-in-loop': 'off',
+      'no-restricted-syntax': 'off',
+      'consistent-return': 'off',
+      'class-methods-use-this': 'off',
+      'no-underscore-dangle': 'off',
+
+      // compat rules to make lint temporarily pass after upgrading to eslint v9 and airbnb-config-extended
+      // these can then get removed one by one to allow for small and focused PRs
+      'import-x/prefer-default-export': strictness,
+      'import-x/order': strictness,
+      'import-x/consistent-type-specifier-style': strictness,
+      'import-x/no-cycle': strictness,
+      'import-x/no-extraneous-dependencies': strictness,
+      'import-x/export': strictness,
+      'import-x/no-namespace': strictness,
+
+      '@typescript-eslint/no-use-before-define': strictness,
+      '@typescript-eslint/consistent-type-definitions': strictness,
+      '@typescript-eslint/explicit-module-boundary-types': strictness,
+      '@typescript-eslint/no-explicit-any': strictness,
+      '@typescript-eslint/ban-ts-comment': strictness,
+      '@typescript-eslint/no-wrapper-object-types': strictness,
+      '@typescript-eslint/consistent-type-imports': strictness,
+      '@typescript-eslint/method-signature-style': strictness,
+      '@typescript-eslint/unified-signatures': strictness,
+      '@typescript-eslint/no-unsafe-return': strictness,
+      '@typescript-eslint/await-thenable': strictness,
+      '@typescript-eslint/prefer-regexp-exec': strictness,
+      '@typescript-eslint/no-confusing-void-expression': strictness,
+      '@typescript-eslint/no-empty-object-type': strictness,
+      '@typescript-eslint/no-import-type-side-effects': strictness,
+      '@typescript-eslint/no-invalid-void-type': strictness,
+      '@typescript-eslint/no-namespace': strictness,
+      '@typescript-eslint/prefer-destructuring': strictness,
+      '@typescript-eslint/consistent-type-assertions': strictness,
+      '@typescript-eslint/no-unnecessary-type-assertion': strictness,
+      '@typescript-eslint/no-non-null-assertion': strictness,
+      '@typescript-eslint/prefer-optional-chain': strictness,
+      '@typescript-eslint/prefer-for-of': strictness,
+      '@typescript-eslint/no-duplicate-type-constituents': strictness,
+      '@typescript-eslint/consistent-indexed-object-style': strictness,
+      '@typescript-eslint/no-unnecessary-boolean-literal-compare': strictness,
+      '@typescript-eslint/class-literal-property-style': strictness,
+      '@typescript-eslint/consistent-generic-constructors': strictness,
+      '@typescript-eslint/promise-function-async': strictness,
+      '@typescript-eslint/no-unsafe-enum-comparison': strictness,
+      '@typescript-eslint/no-redundant-type-constituents': strictness,
+      '@typescript-eslint/prefer-reduce-type-parameter': strictness,
+      '@typescript-eslint/no-unused-vars': strictness,
+      '@typescript-eslint/prefer-includes': strictness,
+      '@typescript-eslint/no-misused-spread': strictness,
+      '@typescript-eslint/consistent-type-exports': strictness,
+      '@typescript-eslint/prefer-function-type': strictness,
+      '@typescript-eslint/prefer-find': strictness,
+
+      '@stylistic/spaced-comment': strictness,
+
+      'no-self-assign': strictness,
+      'no-plusplus': strictness,
+      'no-bitwise': strictness,
+      'no-else-return': strictness,
+      'no-nested-ternary': strictness,
+      'no-promise-executor-return': strictness,
+      'prefer-const': strictness,
+      'prefer-exponentiation-operator': strictness,
+      'no-async-promise-executor': strictness,
+      'no-console': strictness,
+      'no-restricted-properties': strictness,
+      'no-undef-init': strictness,
+      'no-irregular-whitespace': strictness,
+      'object-shorthand': strictness,
+      'no-case-declarations': strictness,
+      'no-useless-escape': strictness,
+      'no-useless-catch': strictness,
+      'no-useless-return': strictness,
+      'no-return-assign': strictness,
+      'no-fallthrough': strictness,
+      'default-case': strictness,
+      'operator-assignment': strictness,
+      'prefer-promise-reject-errors': strictness,
+      'no-continue': strictness,
+      'arrow-body-style': strictness,
+      'no-new': strictness,
+      'vars-on-top': strictness,
+      'no-var': strictness,
+      'no-restricted-globals': strictness,
+      'no-lonely-if': strictness,
+      'no-empty': strictness,
+      'one-var': strictness,
+      'no-multi-assign': strictness,
+      'new-cap': strictness,
+
+      radix: strictness,
+      eqeqeq: strictness,
+
+      // debatable
+      '@typescript-eslint/array-type': 'off',
+      '@typescript-eslint/no-inferrable-types': 'off',
+      '@typescript-eslint/prefer-nullish-coalescing': 'off',
+    },
+  },
+];

examples/rpc/api.ts

@@ -1,7 +1,7 @@
 import dotenv from 'dotenv';
 import express from 'express';
-import type { Express } from 'express';
 import { AccessToken } from 'livekit-server-sdk';
+import type { Express } from 'express';
 
 dotenv.config({ path: '.env.local' });
 

package.json

@@ -51,7 +51,7 @@
     "format:check": "prettier --check src examples/**/*.ts",
     "ci:publish": "pnpm build:clean && pnpm compat && changeset publish",
     "downlevel-dts": "downlevel-dts ./dist/src ./dist/ts4.2 --to=4.2",
-    "compat": "eslint --no-eslintrc --config ./.eslintrc.dist.cjs ./dist/livekit-client.umd.js",
+    "compat": "eslint --config ./eslint.config.dist.mjs --no-inline-config  ./dist/livekit-client.esm.mjs",
     "size-limit": "size-limit"
   },
   "dependencies": {
@@ -74,6 +74,7 @@
     "@babel/preset-env": "7.28.5",
     "@bufbuild/protoc-gen-es": "^1.10.0",
     "@changesets/cli": "2.29.7",
+    "@eslint/js": "9.39.1",
     "@livekit/changesets-changelog-github": "^0.0.4",
     "@rollup/plugin-babel": "6.1.0",
     "@rollup/plugin-commonjs": "28.0.9",
@@ -82,18 +83,20 @@
     "@rollup/plugin-terser": "^0.4.4",
     "@size-limit/file": "^11.2.0",
     "@size-limit/webpack": "^11.2.0",
+    "@stylistic/eslint-plugin": "^3.1.0",
     "@trivago/prettier-plugin-sort-imports": "^5.0.0",
     "@types/events": "^3.0.3",
     "@types/sdp-transform": "2.15.0",
     "@types/ua-parser-js": "0.7.39",
     "@typescript-eslint/eslint-plugin": "7.18.0",
     "@typescript-eslint/parser": "7.18.0",
     "downlevel-dts": "^0.11.0",
-    "eslint": "8.57.1",
-    "eslint-config-airbnb-typescript": "18.0.0",
+    "eslint": "9.39.1",
+    "eslint-config-airbnb-extended": "^2.3.2",
     "eslint-config-prettier": "10.1.8",
-    "eslint-plugin-ecmascript-compat": "^3.2.1",
-    "eslint-plugin-import": "2.32.0",
+    "eslint-plugin-compat": "^6.0.2",
+    "eslint-plugin-import-x": "^4.16.1",
+    "eslint-plugin-prettier": "^5.5.4",
     "gh-pages": "6.3.0",
     "happy-dom": "^17.2.0",
     "jsdom": "^26.1.0",
@@ -105,6 +108,7 @@
     "typedoc": "0.28.14",
     "typedoc-plugin-no-inherit": "1.6.1",
     "typescript": "5.8.3",
+    "typescript-eslint": "^8.47.0",
     "vite": "7.2.2",
     "vitest": "^3.0.0"
   },