Upgrade to eslint 9, use flat config

eslint.config.mjs

@@ -0,0 +1,13 @@
+import { dirname } from 'path';
+import { fileURLToPath } from 'url';
+
+import commonConfig from './shared/config/eslint/common.mjs'
+import govukFrontendConfig from './shared/config/eslint/govuk-frontend-config.mjs'
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+export default [
+  ...commonConfig,
+  ...govukFrontendConfig(__dirname),
+]

package.json

@@ -3,7 +3,7 @@
   "name": "@govuk-frontend/repository",
   "description": "Used only for the development of GOV.UK Frontend, see `packages/govuk-frontend/package.json` for the published `package.json`",
   "engines": {
-    "node": "^20.9.0",
+    "node": "^22.11.0",
     "npm": "^10.1.0"
   },
   "license": "MIT",
@@ -48,40 +48,41 @@
     "prepare": "node -e \"try { (await import('husky')).default() } catch (e) { if (e.code !== 'ERR_MODULE_NOT_FOUND') throw e }\" --input-type module"
   },
   "devDependencies": {
-    "@babel/core": "^7.25.8",
-    "@babel/preset-env": "^7.25.8",
+    "@babel/core": "^7.26.0",
+    "@babel/preset-env": "^7.26.0",
+    "@eslint/js": "^9.13.0",
     "@govuk-frontend/config": "*",
+    "@govuk-frontend/eslint-config": "*",
     "@govuk-frontend/helpers": "*",
     "@govuk-frontend/lib": "*",
     "@govuk-frontend/tasks": "*",
-    "@testing-library/jest-dom": "^6.5.0",
+    "@testing-library/jest-dom": "^6.6.2",
     "@types/testing-library__jest-dom": "^6.0.0",
-    "@typescript-eslint/eslint-plugin": "^7.17.0",
-    "@typescript-eslint/parser": "^7.17.0",
     "concurrently": "^8.2.2",
     "cross-env": "^7.0.3",
     "del-cli": "^5.1.0",
     "editorconfig-checker": "^5.1.8",
-    "eslint": "^8.57.0",
+    "eslint": "^9.13.0",
     "eslint-config-prettier": "^9.1.0",
-    "eslint-config-standard": "^17.1.0",
-    "eslint-plugin-es-x": "^7.6.0",
-    "eslint-plugin-import": "^2.29.1",
-    "eslint-plugin-jest": "^27.9.0",
+    "eslint-plugin-es-x": "^8.0.0",
+    "eslint-plugin-import": "^2.31.0",
+    "eslint-plugin-jest": "^28.8.3",
     "eslint-plugin-jest-dom": "^5.4.0",
-    "eslint-plugin-jsdoc": "^48.2.2",
-    "eslint-plugin-markdown": "^4.0.1",
-    "eslint-plugin-n": "^16.6.2",
-    "eslint-plugin-promise": "^6.1.1",
+    "eslint-plugin-jsdoc": "^50.4.3",
+    "eslint-plugin-markdown": "^5.1.0",
+    "eslint-plugin-n": "^17.11.1",
+    "eslint-plugin-promise": "^7.1.0",
+    "globals": "^15.11.0",
     "gulp": "^5.0.0",
     "gulp-cli": "^3.0.0",
     "husky": "^9.1.6",
     "jest": "^29.7.0",
     "jest-environment-node-single-context": "^29.4.0",
-    "jest-puppeteer": "^10.1.2",
+    "jest-puppeteer": "^10.1.4",
     "jest-regex-util": "^29.4.3",
     "jest-serializer-html": "^7.1.0",
     "lint-staged": "^15.2.10",
+    "neostandard": "^0.11.7",
     "postcss-markdown": "^1.2.0",
     "postcss-scss": "^4.0.9",
     "prettier": "^3.3.3",
@@ -90,7 +91,8 @@
     "stylelint": "^16.9.0",
     "stylelint-config-gds": "^2.0.0",
     "stylelint-order": "^6.0.4",
-    "typescript": "^5.5.4"
+    "typescript": "^5.5.4",
+    "typescript-eslint": "^8.11.0"
   },
   "optionalDependencies": {
     "@actions/github": "^6.0.0",
@@ -100,11 +102,11 @@
     "@types/browser-sync": "^2.29.0",
     "@types/express": "^5.0.0",
     "@types/gulp": "^4.0.17",
-    "@types/jest": "^29.5.13",
+    "@types/jest": "^29.5.14",
     "@types/jest-axe": "^3.5.9",
     "@types/js-yaml": "^4.0.9",
     "@types/mime-types": "^2.1.4",
-    "@types/node": "^22.7.7",
+    "@types/node": "^22.8.1",
     "@types/nunjucks": "^3.2.6",
     "@types/slug": "^5.0.9",
     "@types/vinyl": "^2.0.12",

packages/govuk-frontend/.eslintrc.js

@@ -1,98 +1,98 @@
-const { join } = require('path')
+// const { join } = require('path')
 
-module.exports = {
-  settings: {
-    node: {
-      version: '^18.12.0'
-    }
-  },
-  overrides: [
-    {
-      files: ['src/govuk/**/*.mjs'],
-      excludedFiles: ['**/*.test.mjs'],
-      parser: '@typescript-eslint/parser',
-      parserOptions: {
-        // Note: Allow ES2015 for import/export syntax
-        ecmaVersion: '2015',
-        project: [join(__dirname, 'tsconfig.build.json')]
-      },
-      plugins: ['@typescript-eslint', 'es-x'],
-      extends: [
-        'plugin:@typescript-eslint/strict-type-checked',
-        'plugin:@typescript-eslint/stylistic-type-checked',
-        'plugin:es-x/restrict-to-es2015',
-        'prettier'
-      ],
-      env: {
-        browser: true
-      },
-      rules: {
-        // Allow void return shorthand in arrow functions
-        '@typescript-eslint/no-confusing-void-expression': [
-          'error',
-          {
-            ignoreArrowShorthand: true
-          }
-        ],
+// module.exports = {
+//   settings: {
+//     node: {
+//       version: '^18.12.0'
+//     }
+//   },
+//   overrides: [
+//     {
+//       files: ['src/govuk/**/*.mjs'],
+//       excludedFiles: ['**/*.test.mjs'],
+//       parser: '@typescript-eslint/parser',
+//       parserOptions: {
+//         // Note: Allow ES2015 for import/export syntax
+//         ecmaVersion: '2015',
+//         project: [join(__dirname, 'tsconfig.build.json')]
+//       },
+//       plugins: ['@typescript-eslint', 'es-x'],
+//       extends: [
+//         'plugin:@typescript-eslint/strict-type-checked',
+//         'plugin:@typescript-eslint/stylistic-type-checked',
+//         'plugin:es-x/restrict-to-es2015',
+//         'prettier'
+//       ],
+//       env: {
+//         browser: true
+//       },
+//       rules: {
+//         // Allow void return shorthand in arrow functions
+//         '@typescript-eslint/no-confusing-void-expression': [
+//           'error',
+//           {
+//             ignoreArrowShorthand: true
+//           }
+//         ],
 
-        // Check type support for template string implicit `.toString()`
-        '@typescript-eslint/restrict-template-expressions': [
-          'error',
-          {
-            allowBoolean: true,
-            allowNumber: true
-          }
-        ],
+//         // Check type support for template string implicit `.toString()`
+//         '@typescript-eslint/restrict-template-expressions': [
+//           'error',
+//           {
+//             allowBoolean: true,
+//             allowNumber: true
+//           }
+//         ],
 
-        // Babel transpiles ES2020 class fields
-        'es-x/no-class-fields': 'off',
+//         // Babel transpiles ES2020 class fields
+//         'es-x/no-class-fields': 'off',
 
-        // ES modules include ES2016 '[].includes()' coverage
-        // https://browsersl.ist/#q=supports+es6-module+and+not+supports+array-includes
-        'es-x/no-array-prototype-includes': 'off',
+//         // ES modules include ES2016 '[].includes()' coverage
+//         // https://browsersl.ist/#q=supports+es6-module+and+not+supports+array-includes
+//         'es-x/no-array-prototype-includes': 'off',
 
-        // Babel transpiles ES2020 `??` nullish coalescing
-        'es-x/no-nullish-coalescing-operators': 'off',
+//         // Babel transpiles ES2020 `??` nullish coalescing
+//         'es-x/no-nullish-coalescing-operators': 'off',
 
-        // ES modules include ES2017 'Object.entries()' coverage
-        // https://browsersl.ist/#q=supports+es6-module+and+not+supports+object-entries
-        'es-x/no-object-entries': 'off',
+//         // ES modules include ES2017 'Object.entries()' coverage
+//         // https://browsersl.ist/#q=supports+es6-module+and+not+supports+object-entries
+//         'es-x/no-object-entries': 'off',
 
-        // Babel transpiles ES2020 optional chaining
-        'es-x/no-optional-chaining': 'off',
+//         // Babel transpiles ES2020 optional chaining
+//         'es-x/no-optional-chaining': 'off',
 
-        // JSDoc blocks are mandatory in source code
-        'jsdoc/require-jsdoc': [
-          'error',
-          {
-            enableFixer: false,
-            require: {
-              ClassDeclaration: true,
-              ClassExpression: true,
-              FunctionExpression: false,
-              MethodDefinition: true
-            }
-          }
-        ],
+//         // JSDoc blocks are mandatory in source code
+//         'jsdoc/require-jsdoc': [
+//           'error',
+//           {
+//             enableFixer: false,
+//             require: {
+//               ClassDeclaration: true,
+//               ClassExpression: true,
+//               FunctionExpression: false,
+//               MethodDefinition: true
+//             }
+//           }
+//         ],
 
-        // JSDoc @param required in (mandatory) blocks but
-        // @param description is necessary in source code
-        'jsdoc/require-param-description': 'warn',
-        'jsdoc/require-param': 'error'
-      }
-    },
-    {
-      files: ['src/govuk-prototype-kit/**/*.js'],
-      parserOptions: {
-        sourceType: 'module'
-      },
-      env: {
-        browser: true
-      },
-      rules: {
-        // Allow browser import `govuk-frontend.min.js`
-        'n/no-missing-import': 'off'
-      }
-    }
-  ]
-}
+//         // JSDoc @param required in (mandatory) blocks but
+//         // @param description is necessary in source code
+//         'jsdoc/require-param-description': 'warn',
+//         'jsdoc/require-param': 'error'
+//       }
+//     },
+//     {
+//       files: ['src/govuk-prototype-kit/**/*.js'],
+//       parserOptions: {
+//         sourceType: 'module'
+//       },
+//       env: {
+//         browser: true
+//       },
+//       rules: {
+//         // Allow browser import `govuk-frontend.min.js`
+//         'n/no-missing-import': 'off'
+//       }
+//     }
+//   ]
+// }

packages/govuk-frontend/eslint.config.mjs

@@ -0,0 +1,18 @@
+import { dirname } from 'path';
+import { fileURLToPath } from 'url';
+
+import commonConfig from './../../shared/config/eslint/common.mjs';
+import govukFrontendConfig from './../../shared/config/eslint/govuk-frontend-config.mjs';
+
+import { common, govukFrontendConfig } from '@govuk-frontend/eslint-config'
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+console.log('ayy')
+console.log(__dirname)
+
+export default [
+  ...commonConfig,
+  ...govukFrontendConfig(__dirname),
+]

packages/govuk-frontend/package.json

@@ -65,6 +65,7 @@
     "@babel/core": "^7.25.8",
     "@babel/preset-env": "^7.25.8",
     "@govuk-frontend/config": "*",
+    "@govuk-frontend/eslint-config": "*",    
     "@govuk-frontend/helpers": "*",
     "@govuk-frontend/lib": "*",
     "@govuk-frontend/tasks": "*",
@@ -87,6 +88,7 @@
     "sass-color-helpers": "^2.1.1",
     "sass-embedded": "^1.79.4",
     "sassdoc": "^2.7.4",
-    "slash": "^5.1.0"
+    "slash": "^5.1.0",
+    "typescript-eslint": "^8.13.0"
   }
 }