Move to ESM and flat config

Fixes #2278

Author: sindresorhus

.eslint-doc-generatorrc.js

@@ -2,20 +2,24 @@
 
 /** @type {import('eslint-doc-generator').GenerateOptions} */
 const config = {
-  ignoreConfig: ['all', 'flat/all', 'flat/recommended'],
-  ignoreDeprecatedRules: true,
-  ruleDocTitleFormat: 'desc',
-  ruleListColumns: [
-    'name',
-    'description',
-    'configsError',
-    // Omit `configsOff` since we don't intend to convey meaning by setting rules to `off` in the `recommended` config.
-    'configsWarn',
-    'fixable',
-    'hasSuggestions',
-    'requiresTypeChecking',
-  ],
-  urlConfigs: 'https://github.com/sindresorhus/eslint-plugin-unicorn#preset-configs-eslintconfigjs',
+	ignoreConfig: [
+		'all',
+		'flat/all',
+		'flat/recommended',
+	],
+	ignoreDeprecatedRules: true,
+	ruleDocTitleFormat: 'desc',
+	ruleListColumns: [
+		'name',
+		'description',
+		'configsError',
+		// Omit `configsOff` since we don't intend to convey meaning by setting rules to `off` in the `recommended` config.
+		'configsWarn',
+		'fixable',
+		'hasSuggestions',
+		'requiresTypeChecking',
+	],
+	urlConfigs: 'https://github.com/sindresorhus/eslint-plugin-unicorn#preset-configs-eslintconfigjs',
 };
 
-module.exports = config;
+export default config;

.github/workflows/main.yml

@@ -15,8 +15,7 @@ jobs:
       fail-fast: false
       matrix:
         node-version:
-          - 20
-          - 18
+          - 23
         os:
           - ubuntu-latest
           - windows-latest
@@ -43,7 +42,7 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           # Locked due to the difference of `zlib.gzipSync()` between Node.js versions
-          node-version: 20
+          node-version: 23
       - run: npm install
       - run: npm run lint
       - run: npx del-cli test/snapshots --verbose
@@ -62,6 +61,8 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
+        with:
+          node-version: 23
       - run: npm install
       - run: npm run run-rules-on-codebase
   integration:
@@ -85,5 +86,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
+        with:
+          node-version: 23
       - run: npm install
       - run: npm run integration -- --group ${{ matrix.group }}

configs/flat-config-base.js

@@ -1,8 +1,9 @@
-'use strict';
-const globals = require('globals');
+import globals from 'globals';
 
-module.exports = {
+const config = {
 	languageOptions: {
 		globals: globals.builtin,
 	},
 };
+
+export default config;

configs/legacy-config-base.js

@@ -13,7 +13,7 @@ Use the [`astexplorer` site](https://astexplorer.net) with the `espree` parser a
 ## Steps
 
 - Run `npm run create-rule` to create files for the new rule.
-- Open “test/{RULE_ID}.mjs” and [write some tests](./write-tests.md) before implementing the rule.
+- Open “test/{RULE_ID}.js” and [write some tests](./write-tests.md) before implementing the rule.
 - Open “rules/{RULE_ID}.js” and implement the rule logic.
 - Add the correct [`meta.type`](https://eslint.org/docs/developer-guide/working-with-rules#rule-basics) to the rule.
 - Open “docs/rules/{RULE_ID}.js” and write some documentation.

docs/new-rule.md

@@ -12,13 +12,15 @@ Passing functions to iterator methods can cause issues when the function is chan
 Suppose you have a `unicorn` module:
 
 ```js
-module.exports = x => x + 1;
+const unicorn = x => x + 1;
+
+export default unicorn;
 ```
 
 You can then use it like this:
 
 ```js
-const unicorn = require('unicorn');
+import unicorn from 'unicorn';
 
 [1, 2, 3].map(unicorn);
 //=> [2, 3, 4]
@@ -27,13 +29,15 @@ const unicorn = require('unicorn');
 The `unicorn` module now does a minor version that adds another argument:
 
 ```js
-module.exports = (x, y) => x + (y ? y : 1);
+const unicorn = (x, y) => x + (y ? y : 1);
+
+export default unicorn;
 ```
 
 Your code will now return something different and probably break for users because it is now passing the index of the item as second argument.
 
 ```js
-const unicorn = require('unicorn');
+import unicorn from 'unicorn';
 
 [1, 2, 3].map(unicorn);
 //=> [2, 3, 5]
@@ -42,7 +46,7 @@ const unicorn = require('unicorn');
 This rule helps safely call the function with the expected number of parameters:
 
 ```js
-const unicorn = require('unicorn');
+import unicorn from 'unicorn';
 
 [1, 2, 3].map(x => unicorn(x));
 //=> [2, 3, 4]

docs/rules/no-array-callback-reference.md

@@ -26,7 +26,7 @@ package.json
 ```
 
 ```js
-const assign = require('object-assign');
+import assign from 'object-assign';
 ```
 
 ## Pass
@@ -42,7 +42,7 @@ package.json
 ```
 
 ```js
-const assign = require('object-assign'); // Passes as Object.assign is not supported
+import assign from 'object-assign'; // Passes as Object.assign is not supported
 ```
 
 ## Options

docs/rules/no-unnecessary-polyfills.md

@@ -69,7 +69,8 @@ This option lets you specify a list of packages that disable the rule when impor
 With `koa`, this would still pass:
 
 ```js
-const Koa = require('koa');
+import Koa from 'koa';
+
 const app = new Koa();
 
 app.onerror = () => {};

docs/rules/prefer-add-event-listener.md

@@ -9,12 +9,6 @@
 
 When importing builtin modules, it's better to use the [`node:` protocol](https://nodejs.org/api/esm.html#node-imports) as it makes it perfectly clear that the package is a Node.js builtin module.
 
-Note that Node.js support for this feature began in:
-
-> v16.0.0, v14.18.0 (`require()`)
->
-> v14.13.1, v12.20.0 (`import`)
-
 ## Fail
 
 ```js
@@ -29,14 +23,6 @@ export {strict as default} from 'assert';
 import fs from 'fs/promises';
 ```
 
-```js
-const fs = require('fs');
-```
-
-```js
-const fs = require('fs/promises');
-```
-
 ## Pass
 
 ```js
@@ -58,7 +44,3 @@ import _ from 'lodash';
 ```js
 import fs from './fs.js';
 ```
-
-```js
-const fs = require('node:fs/promises');
-```

docs/rules/prefer-node-protocol.md

@@ -188,10 +188,6 @@ import tempWrite from 'temp-write';
 import * as err from 'err';
 ```
 
-```js
-const err = require('err');
-```
-
 ### checkShorthandImports
 
 Type: `'internal'` | `boolean`\
@@ -222,10 +218,6 @@ Pass `"checkShorthandProperties": true` to check variables declared as shorthand
 
 With this set to `true` the following code will be reported.
 
-```js
-const {prop} = require('ramda');
-```
-
 ```js
 const {err} = foo;
 ```