feat: support flat config

Resolves: amilajack#603

package.json

@@ -78,6 +78,7 @@
     "browserslist": "^4.23.0",
     "caniuse-lite": "^1.0.30001594",
     "find-up": "^5.0.0",
+    "globals": "^13.24.0",
     "lodash.memoize": "^4.1.2",
     "semver": "^7.6.0"
   },

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 { ESLint, Linter } from "eslint";
 
 //------------------------------------------------------------------------------
 // Plugin Definition
@@ -15,13 +17,33 @@ 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: ESLint.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 }),
+  // Kept for backwards compatibility
+  config: configs,
 };

src/rules/compat.ts

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

tsconfig.build.json

@@ -1,4 +1,7 @@
 {
   "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "./src"
+  },
   "include": ["src"]
 }