feat: support flat config (#609)

* chore: bump deps

* test: update snapshots

* chore: babel-eslint to @babel/eslint-parser

* feat: support flat config

Resolves: #603

* test: add typing tests for flat configs

* docs: add flat config example to README

* chore: deprecate named export

* feat: provide type declaration

* 5.0.0-0

* fix: add esm/cjs support

* 5.0.0-1

* 5.0.0-2

---------

Co-authored-by: Amila Welihinda <[email protected]>

README.md

@@ -21,7 +21,17 @@ npm install eslint-plugin-compat
 
 ### 2. Update ESLint Config
 
-#### `.eslintrc.json`
+#### New Config (`eslint.config.mjs`)
+
+```js
+import compat from "eslint-plugin-compat"
+
+export default [
+  compat.configs['flat/recommended']
+];
+```
+
+#### Legacy Config (`.eslintrc.json`)
 
 ```jsonc
 {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "eslint-plugin-compat",
-  "version": "4.2.0",
+  "version": "5.0.0-2",
   "description": "Lint browser compatibility of API used",
   "keywords": [
     "eslint",
@@ -25,13 +25,26 @@
     "Amila Welihinda <[email protected]> (https://github.com/amilajack)",
     "John Tran <[email protected]> (https://github.com/jooohhn)"
   ],
-  "main": "lib/index.js",
+  "main": "./lib/cjs/src/index.js",
+  "types": "./lib/cjs/src/index.d.ts",
+  "exports": {
+    ".": {
+      "import": {
+        "types": "./lib/esm//src/index.d.mts",
+        "default": "./lib/esm/src/index.js"
+      },
+      "require": {
+        "types": "./lib/cjs/src/index.d.ts",
+        "default": "./lib/cjs/src/index.js"
+      }
+    }
+  },
   "files": [
     "lib"
   ],
   "scripts": {
     "benchmarks": "ts-node-transpile-only test/benchmarks.ts",
-    "build": "rm -rf lib && tsc --project tsconfig.build.json",
+    "build": "rm -rf lib && tsc --project tsconfig.build.json && tsc --project tsconfig.esm.json",
     "lint": "eslint --ignore-path .gitignore --ext .js,.ts .",
     "spec": "jest --testPathIgnorePatterns test/e2e-repo.spec.ts /benchmarks-tmp",
     "spec:e2e": "jest test/e2e-repo.spec.ts",
@@ -73,45 +86,48 @@
     ]
   },
   "dependencies": {
-    "@mdn/browser-compat-data": "^5.3.16",
+    "@mdn/browser-compat-data": "^5.5.19",
     "ast-metadata-inferer": "^0.8.0",
-    "browserslist": "^4.21.10",
-    "caniuse-lite": "^1.0.30001534",
+    "browserslist": "^4.23.0",
+    "caniuse-lite": "^1.0.30001605",
     "find-up": "^5.0.0",
+    "globals": "^13.24.0",
     "lodash.memoize": "^4.1.2",
-    "semver": "^7.5.4"
+    "semver": "^7.6.0"
   },
   "devDependencies": {
+    "@babel/core": "^7.24.3",
+    "@babel/eslint-parser": "^7.24.1",
     "@semantic-release/changelog": "^6.0.3",
     "@semantic-release/git": "^10.0.1",
-    "@tsconfig/node16": "^16.1.1",
-    "@types/benchmark": "^2.1.3",
-    "@types/browserslist": "^4.15.0",
-    "@types/caniuse-lite": "^1.0.2",
-    "@types/eslint": "^8.44.2",
-    "@types/jest": "^29.5.5",
-    "@types/lodash.memoize": "^4.1.7",
-    "@types/semver": "7.5.2",
-    "@typescript-eslint/eslint-plugin": "^6.7.0",
-    "@typescript-eslint/parser": "^6.7.0",
-    "babel-eslint": "^10.1.0",
+    "@tsconfig/node16": "^16.1.3",
+    "@types/benchmark": "^2.1.5",
+    "@types/caniuse-lite": "^1.0.5",
+    "@types/eslint": "^8.56.7",
+    "@types/jest": "^29.5.12",
+    "@types/lodash.memoize": "^4.1.9",
+    "@types/semver": "7.5.8",
+    "@typescript-eslint/eslint-plugin": "^7.5.0",
+    "@typescript-eslint/parser": "^7.5.0",
     "benchmark": "^2.1.4",
     "browserslist-config-erb": "^0.0.3",
-    "electron": "^26.x.x",
-    "eslint": "^8.49.0",
-    "eslint-config-airbnb-typescript": "^17.1.0",
+    "electron": "^29.x.x",
+    "eslint": "^8.57.0",
+    "eslint-config-airbnb-typescript": "^18.0.0",
     "eslint-config-bliss-typescript": "^6.0.2",
-    "eslint-config-prettier": "^9.0.0",
-    "eslint-plugin-eslint-plugin": "^5.1.1",
-    "eslint-plugin-import": "^2.28.1",
-    "eslint-plugin-prettier": "^5.0.0",
+    "eslint-config-prettier": "^9.1.0",
+    "eslint-plugin-eslint-plugin": "^5.5.0",
+    "eslint-plugin-import": "^2.29.1",
+    "eslint-plugin-prettier": "^5.1.3",
+    "expect-type": "^0.19.0",
     "jest": "^29.7.0",
-    "prettier": "^3.0.3",
-    "semantic-release": "^22.0.0",
-    "simple-git": "^3.19.1",
-    "ts-jest": "^29.1.1",
-    "ts-node": "^10.9.1",
-    "typescript": "^5.2.2"
+    "prettier": "^3.2.5",
+    "semantic-release": "^22.0.12",
+    "simple-git": "^3.24.0",
+    "ts-jest": "^29.1.2",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.4.3",
+    "typescript-eslint": "^7.5.0"
   },
   "peerDependencies": {
     "eslint": "^4.0.0 || ^5.0.0 || ^6.0.0 || ^7.0.0 || ^8.0.0"

src/config/recommended.ts

@@ -1,10 +1,33 @@
-// Reconmmended configs for this plugin
-export default {
-  plugins: ["compat"],
-  env: {
-    browser: true,
+/**
+ * @file Recommended configs for this plugin
+ */
+
+import globals from "globals";
+import type { ESLint, Linter } from "eslint";
+
+// Flat config: https://eslint.org/docs/latest/use/configure/configuration-files-new
+const flat = {
+  languageOptions: {
+    globals: {
+      ...globals.browser,
+    },
   },
   rules: {
     "compat/compat": "error",
   },
+} satisfies Linter.FlatConfig;
+
+// eslintrc config: https://eslint.org/docs/latest/use/configure/configuration-files
+const legacy = {
+  env: {
+    browser: true,
+  },
+  rules: flat.rules,
+} satisfies ESLint.ConfigData;
+
+const recommended = {
+  flat,
+  legacy,
 };
+
+export default recommended;

src/index.ts

@@ -7,6 +7,8 @@
 // Requirements
 //------------------------------------------------------------------------------
 import recommended from "./config/recommended";
+import pkg from "../package.json";
+import type { Linter } from "eslint";
 
 //------------------------------------------------------------------------------
 // Plugin Definition
@@ -15,13 +17,36 @@ import recommended from "./config/recommended";
 // import all rules in lib/rules
 import compat from "./rules/compat";
 
-export const configs = {
-  recommended,
+const rules = {
+  compat,
 };
 
-// Kept for backwards compatibility
-export const config = configs;
+const plugin = {
+  meta: {
+    name: pkg.name,
+    version: pkg.version,
+  },
+  configs: {},
+  rules,
+};
 
-export const rules = {
-  compat,
+const configs = {
+  "flat/recommended": {
+    plugins: { compat: plugin },
+    ...recommended.flat,
+  } as Linter.FlatConfig,
+  recommended: {
+    plugins: ["compat"],
+    ...recommended.legacy,
+  } as Linter.Config,
+};
+plugin.configs = configs;
+
+export = {
+  ...(plugin as typeof plugin & { configs: typeof configs }),
+  // TODO: Remove this in next major release
+  /**
+   * @deprecated Use `.configs` instead. This will be removed in the next major release.
+   */
+  config: configs,
 };

src/rules/compat.ts

@@ -267,4 +267,4 @@ export default {
       },
     };
   },
-};
+} as Rule.RuleModule;