Convert to new flat config for eslint

eslint.config.js

@@ -0,0 +1,22 @@
+// @ts-check
+
+import eslint   from '@eslint/js';
+import tseslint from 'typescript-eslint';
+
+export default [
+   eslint.configs.recommended,
+   ...tseslint.configs.strictTypeChecked,
+   { ignores: ['**/*.js'] },
+   {
+      languageOptions: { parserOptions: { projectService: true } },
+      rules: {
+         '@typescript-eslint/no-confusing-void-expression':           'off',  //prefer minimal arrow functions
+         '@typescript-eslint/no-floating-promises':                   'off',  //annimations may be fire-and-forget
+         '@typescript-eslint/no-misused-promises':                    'off',  //annimations may be fire-and-forget
+         '@typescript-eslint/no-non-null-assertion':                  'off',  //ts cannot always know value exists
+         '@typescript-eslint/restrict-template-expressions':          'off',  //numbers in templates are natural
+         '@typescript-eslint/unbound-method':                         'off',  //safer to not use 'this'
+         '@typescript-eslint/use-unknown-in-catch-callback-variable': 'off',  //clarity over theoretical exceptions
+         },
+      },
+   ];

hello-world/package.json

@@ -30,7 +30,7 @@
       "assert-deep-strict-equal": "~1.2",
       "fetch-json": "~3.3",
       "jshint": "~2.13",
-      "mocha": "~10.4",
+      "mocha": "~10.7",
       "server-listening": "~1.2"
    }
 }

package.json

@@ -41,32 +41,13 @@
       "mocha": true,
       "node": true
    },
-   "eslintConfig": {
-      "ignorePatterns": [
-         "build",
-         "dist",
-         "node_modules"
-      ],
-      "root": true,
-      "parser": "@typescript-eslint/parser",
-      "plugins": [
-         "@typescript-eslint"
-      ],
-      "extends": [
-         "eslint:recommended",
-         "plugin:@typescript-eslint/recommended"
-      ],
-      "rules": {
-         "@typescript-eslint/no-non-null-assertion": "off"
-      }
-   },
    "runScriptsConfig": {
       "clean": [
          "rimraf build dist"
       ],
       "lint": [
          "jshint . --exclude-path .gitignore",
-         "eslint --max-warnings 0 . --ext .ts"
+         "eslint --max-warnings 0"
       ],
       "build": [
          "tsc"
@@ -86,22 +67,22 @@
       "jsdom": "~24.1"
    },
    "devDependencies": {
-      "@eslint/js": "~9.3",
+      "@eslint/js": "~9.9",
       "@types/express": "~4.17",
       "@types/jsdom": "~21.1",
-      "@types/node": "~20.12",
+      "@types/node": "~22.2",
       "add-dist-header": "~1.4",
       "assert-deep-strict-equal": "~1.2",
       "copy-file-util": "~1.2",
       "copy-folder-util": "~1.1",
-      "eslint": "8.57.0",
+      "eslint": "~9.9",
       "fetch-json": "~3.3",
       "jshint": "~2.13",
-      "mocha": "~10.4",
-      "rimraf": "~5.0",
-      "run-scripts-util": "~1.2",
-      "typescript": "~5.4",
-      "typescript-eslint": "~7.11",
+      "mocha": "~10.7",
+      "rimraf": "~6.0",
+      "run-scripts-util": "~1.3",
+      "typescript": "~5.5",
+      "typescript-eslint": "~8.1",
       "w3c-html-validator": "~1.8"
    }
 }

server-listening.ts

@@ -55,15 +55,15 @@ const serverListening = {
       return new Promise(resolve => server.close(resolve));
       },
    jsdomOnLoad(dom: JSDOM): Promise<JSDOM> {
-      const name = dom && dom.constructor && dom.constructor.name;
+      const name = (<unknown>dom)?.constructor?.name;
       if (name !== 'JSDOM')
-         throw Error(`[server-listening] Unable to load DOM: ${name} => ${String(dom)}`);
+         throw new Error(`[server-listening] Unable to load DOM: ${String(dom)} => ${name}`);
       let done: (jsdom: JSDOM) => void;
       dom.window.onload = () => done(dom);
       return new Promise(resolve => done = resolve);
       },
    jsdomCloseWindow(dom: JSDOM): Promise<JSDOM> {
-      if (dom)
+      if (<unknown>dom)
          dom.window.close();
       return new Promise(resolve => resolve(dom));
       },

spec/package.spec.js

@@ -89,7 +89,7 @@ describe('The jsdomOnLoad() function', () => {
 
    it('throws an error if the DOM is missing', () => {
       const callhandleDom = () => serverListening.jsdomOnLoad(null);
-      const exception = { message: '[server-listening] Unable to load DOM: null => null' };
+      const exception = { message: '[server-listening] Unable to load DOM: null => undefined' };
       assert.throws(callhandleDom, exception);
       });