feat!: ESLint 9 Fixes (#307)

* chore: update postinstall scripts
* chore(lint): eslint automated fixes
* feat!: drop standard, sonarjs to work with eslint9

- This config allows arrow functions.

BREAKING CHANGES:

- Switches to eslint-config-eslint from eslint-config-standard.
- Also drops eslint-plugins-sonarjs because it doesn't work well
  with eslint9, and wants eslint8 and related plugins.
- Switches from eslint-plugin-prettier to eslint-config-prettier.

packages/eslint-config/README.md

@@ -26,7 +26,7 @@ npm install @ivuorinen/eslint-config --save-dev
 yarn add @ivuorinen/eslint-config --dev
 ```
 
-After installing it, a _`.eslintrc.json`_ file will be created automatically in the project's root folder with the following configuration:
+After installing it, a _`eslint.config.mjs`_ file will be created automatically in the project's root folder with the following configuration:
 
 ```json
 {

packages/eslint-config/index.cjs

@@ -1,16 +1,32 @@
+'use strict'
+
 const globals = require('globals')
+const configEslint = require('eslint-config-eslint')
+const configPrettier = require('eslint-config-prettier')
+const pluginImport = require('eslint-plugin-import')
 const pluginJs = require('@eslint/js')
-const standard = require('eslint-config-standard')
 const pluginN = require('eslint-plugin-n')
 const pluginPromise = require('eslint-plugin-promise')
-const pluginImport = require('eslint-plugin-import')
-const pluginPrettier = require('eslint-plugin-prettier')
-const pluginSonarJS = require('eslint-plugin-sonarjs')
 
 /**
  * @type { import("eslint").Linter.Config[] } config eslint configuration.
  */
 module.exports = [
+  ...configEslint,
+  {
+    linterOptions: {
+      reportUnusedDisableDirectives: 'warn'
+    },
+    rules: {
+      'func-style': [
+        'error',
+        'declaration',
+        {
+          allowArrowFunctions: true
+        }
+      ]
+    }
+  },
   {
     files: ['**/*.{js,mjs,cjs}'],
     languageOptions: {
@@ -30,12 +46,10 @@ module.exports = [
     plugins: {
       n: pluginN,
       import: pluginImport,
-      promise: pluginPromise,
-      prettier: pluginPrettier,
-      sonarjs: pluginSonarJS
-    },
-    rules: standard.rules
+      promise: pluginPromise
+    }
   },
+  configPrettier,
   {
     ignores: ['coverage/', 'dist/', 'lib/', 'node_modules/']
   }

packages/eslint-config/jest.cjs

@@ -1,3 +1,5 @@
+'use strict'
+
 const jest = require('eslint-plugin-jest')
 
 /**

packages/eslint-config/package.json

@@ -53,15 +53,15 @@
   "dependencies": {
     "@eslint/js": "^9",
     "@ivuorinen/config-checker": "^1.1.8",
-    "eslint": "^9",
+    "eslint": "^9.15.0",
+    "eslint-config-eslint": "^11",
     "eslint-config-prettier": "^9",
-    "eslint-config-standard": "^17",
     "eslint-plugin-import": "^2",
     "eslint-plugin-jest": "^28",
     "eslint-plugin-n": "^17",
     "eslint-plugin-promise": "^7",
-    "eslint-plugin-sonarjs": "^2",
-    "globals": "^15"
+    "globals": "^15",
+    "typescript": ">=4.2.0"
   },
   "gitHead": "23d15f15743fb59c1dbe658615ef2ed51c54d230"
 }

packages/eslint-config/scripts/postinstall.cjs

@@ -1,9 +1,10 @@
 'use strict'
 
-const fs = require('fs')
-const path = require('path')
-// noinspection NpmUsedModulesInstalled
-const process = require('process')
+/* eslint no-console: "off", n/no-process-exit: "off" -- CLI app that gives users feedback */
+
+const fs = require('node:fs')
+const path = require('node:path')
+const process = require('node:process')
 const checkConfig = require('@ivuorinen/config-checker')
 const foundConfig = checkConfig('eslint')