chore: upgrade to eslint 9 #1426

Author: erossignon

.eslintignore

@@ -0,0 +1,149 @@
+import path from "path";
+import { fileURLToPath } from "url";
+
+import { defineConfig, globalIgnores } from "eslint/config";
+
+import tsParser from "@typescript-eslint/parser";
+import typescriptEslint from "@typescript-eslint/eslint-plugin";
+import unusedImports from "eslint-plugin-unused-imports";
+import workspaces from "eslint-plugin-workspaces";
+import notice from "eslint-plugin-notice";
+import globals from "globals";
+import js from "@eslint/js";
+import reactNamingConvention from "eslint-plugin-react-naming-convention";
+import extraneousDependencies from "eslint-plugin-import";
+import { FlatCompat } from "@eslint/eslintrc";
+import nodePlugin from "eslint-plugin-n";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+const compat = new FlatCompat({
+    baseDirectory: __dirname,
+    recommendedConfig: js.configs.recommended,
+    allConfig: js.configs.all,
+});
+
+export default defineConfig([
+    ...compat.extends(
+        "eslint:recommended",
+        "prettier",
+        "plugin:@typescript-eslint/recommended",
+        "plugin:workspaces/recommended",
+        "plugin:n/recommended"
+    ),
+    //
+    nodePlugin.configs["flat/recommended-script"],
+    {
+        languageOptions: {
+            parser: tsParser,
+            parserOptions: {
+                tsconfigRootDir: __dirname,
+                project: ["./tsconfig.eslint.json"],
+            },
+            globals: {
+                ...globals.node,
+            },
+        },
+        plugins: {
+            "@typescript-eslint": typescriptEslint,
+            "unused-imports": unusedImports,
+            workspaces,
+            notice,
+            "react-naming-convention": reactNamingConvention,
+            "extraneous-dependencies": extraneousDependencies,
+            n: nodePlugin,
+        },
+
+        rules: {
+            // *************** Ensure that copyright notice is present ***************
+            "notice/notice": [
+                "error",
+                {
+                    mustMatch: "Copyright \\(c\\) [0-9]{0,4} Contributors to the Eclipse Foundation",
+                    templateFile: __dirname + "/license.template.txt",
+                    onNonMatchingHeader: "replace",
+                },
+            ],
+
+            // *************** NodeJS specific rules - relaxing default setting of n  ***************cs
+            "n/no-path-concat": "error",
+            "n/no-unsupported-features/es-syntax": [
+                "error",
+                {
+                    ignores: ["modules"],
+                },
+            ],
+
+            // relax missing import rule to warning, as we sometimes have optional dependencies
+            // import "../foo" will braise a warning ,
+            // import "../foo.js" is the correct way to import a file that may not exist
+            "n/no-missing-import": "warn",
+
+            "n/no-unsupported-features/node-builtins": "warn",
+            "n/no-extraneous-import": "warn",
+            "n/no-deprecated-api": "warn",
+            "n/no-unpublished-import": "warn",
+            "n/no-process-exit": "warn",
+            "n/hashbang": "warn",
+
+            // *************** Ensure that only used dependencies are imported ***************
+            "extraneous-dependencies/no-extraneous-dependencies": "warn",
+
+            // *************** Code style and best practices ***************
+            "unused-imports/no-unused-imports": "error",
+            "unused-imports/no-unused-vars": [
+                "warn",
+                {
+                    args: "none",
+                    varsIgnorePattern: "Test",
+                },
+            ],
+
+            // **************** enforece kebab-case for filenames ****************
+            "react-naming-convention/filename": [
+                "warn",
+                {
+                    rule: "kebab-case",
+                },
+            ],
+
+            // *************** Customization of other typescript rules ***************
+            "@typescript-eslint/no-use-before-define": "error",
+            "@typescript-eslint/no-unused-vars": "off",
+            "@typescript-eslint/no-unused-expressions": "off",
+            "@typescript-eslint/no-require-imports": "warn",
+            "@typescript-eslint/prefer-nullish-coalescing": "warn",
+            "@typescript-eslint/no-empty-object-type": "warn",
+
+            // ****************  Enforce usage of `const` over `let` wherever possible, to prevent accidental reassignments
+            "prefer-const": "warn",
+
+            // *************** Other rules ***************
+            "no-restricted-globals": "error",
+            "no-restricted-properties": "error",
+
+            "no-use-before-define": "error",
+
+            "no-unused-private-class-members": "warn",
+            "no-prototype-builtins": "off",
+            "no-case-declarations": "off",
+
+            // ***************** Enforce that for-in loops include an if statement to filter properties from the prototype chain
+            "guard-for-in": "error",
+        },
+    },
+    globalIgnores([
+        "utils/*",
+        "packages/browser-bundle/types/index.d.ts",
+        "packages/*/eslint.config.mjs",
+        "eslint.config.mjs",
+        "packages/browser-bundle/web-test-runner.config.mjs",
+        "**/.eslintrc.js",
+        "**/dist",
+        "**/node_modules",
+        "examples",
+        "**/bin",
+        "**/*.js",
+    ]),
+]);