feat: update typescript config

- switch to eslint flat config
- migrate from old @typescript-eslint/* to the new typescript-eslint
- migrate from old @angular-eslint/* to the new angular-eslint
- bump minimum eslint version to 9.20
- add extensions to @typescript-eslint/no-unused-vars starting with _
- move from cmj to esm
- add index.d.ts file

Author: robertIsaac

eslint-config-typescript/index.d.ts

@@ -0,0 +1,5 @@
+import { ConfigArray } from "typescript-eslint";
+
+declare const _default: ConfigArray;
+
+export default _default;

eslint-config-typescript/index.js

@@ -1,28 +1,39 @@
-module.exports = {
-  root: true,
-  overrides: [
+// @ts-check
+import pluginTs from "typescript-eslint";
+import pluginJs from "@eslint/js";
+import pluginJest from "eslint-plugin-jest";
+import pluginPrettier from "eslint-config-prettier";
+
+export default pluginTs.config(
+    // config to all javascript and typescript files
     {
-      files: ["*.ts"],
-      parserOptions: {
-        project: ["tsconfig.json"],
-        createDefaultProgram: true,
-      },
-      extends: [
-        "eslint:recommended",
-        "plugin:@typescript-eslint/recommended",
-        "plugin:@typescript-eslint/recommended-requiring-type-checking",
-        "plugin:prettier/recommended",
-        "prettier",
-      ],
+        files: ["**/*.ts", "**/*.js"],
+        extends: [pluginJs.configs.recommended, pluginPrettier],
+        rules: {
+            "no-duplicate-imports": "error",
+        }
     },
     {
-      files: ["*.spec.ts"],
-      plugins: ["jest"],
+        // config to all typescript files only
+        files: ["**/*.ts"],
+        extends: [pluginTs.configs.recommended, pluginTs.configs.stylistic],
+        rules: {
+            "@typescript-eslint/no-unused-vars": [
+                "error",
+                {
+                    argsIgnorePattern: '^_',
+                    caughtErrorsIgnorePattern: '^_',
+                    ignoreRestSiblings: true,
+                },
+            ],
+        }
+    },
+    {
+      // config to test files only
+      files: ['**/*.spec.ts'],
+      ...pluginJest.configs['flat/recommended'],
       rules: {
-        // See also https://github.com/jest-community/eslint-plugin-jest/blob/main/docs/rules/unbound-method.md
-        "@typescript-eslint/unbound-method": "off",
-        "jest/unbound-method": "error",
-      },
+        ...pluginJest.configs['flat/recommended'].rules,
+      }
     },
-  ],
-};
+);

eslint-config-typescript/package.json

@@ -4,7 +4,8 @@
   "description": "Repository which contains ESLint Configuration for projects that use TypeScript",
   "main": "index.js",
   "files": [
-    "index.js"
+    "index.js",
+    "index.d.ts"
   ],
   "scripts": {
     "build": "echo 'No build required'",
@@ -14,22 +15,12 @@
     "node": ">=18.0.0",
     "npm": ">=9.0.0"
   },
-  "devDependencies": {
-    "@typescript-eslint/eslint-plugin": "8.24.1",
-    "@typescript-eslint/parser": "8.24.1",
-    "eslint": "9.20.1",
-    "eslint-config-prettier": "10.0.1",
-    "eslint-plugin-jest": "28.11.0",
-    "eslint-plugin-prettier": "5.2.3",
-    "prettier": "3.5.1"
-  },
   "peerDependencies": {
-    "@typescript-eslint/eslint-plugin": ">=8.0.0",
-    "@typescript-eslint/parser": ">=8.0.0",
-    "eslint": ">=9.0.0",
-    "eslint-config-prettier": ">=9.0.0",
-    "eslint-plugin-jest": ">=25.2.2",
-    "eslint-plugin-prettier": ">=4.2.1",
-    "prettier": ">=2.4.1"
-  }
+    "eslint": "^9.20.0",
+    "eslint-config-prettier": "^10.0.1",
+    "eslint-plugin-jest": "^28.11.0",
+    "@eslint/js": "^9.20.0",
+    "typescript-eslint": "^8.24.0"
+  },
+  "type": "module"
 }