Support flat config

packages/eslint-config-airbnb-base/README.md

@@ -62,6 +62,28 @@ Our default export contains all of our ESLint rules, including ECMAScript 6+. It
 
 2. Add `"extends": "airbnb-base"` to your .eslintrc.
 
+  If using **flat config**, add `eslint-config-airbnb-base/flat` to `eslint.config.mjs` / `eslint.config.cjs` / `eslint.config.js` :
+
+  ```js
+  // eslint.config.cjs
+  const airbnbBase = require('eslint-config-airbnb-base/flat');
+
+  module.exports = [
+    ...airbnbBase,
+    // ......
+  ];
+  ```
+
+  ```js
+  // eslint.config.mjs
+  import airbnbBase from 'eslint-config-airbnb-base/flat';
+
+  export default [
+    ...airbnbBase,
+    // ......
+  ];
+  ```
+
 ### eslint-config-airbnb-base/legacy
 
 Lints ES5 and below. Requires `eslint` and `eslint-plugin-import`.
@@ -94,6 +116,27 @@ See [Airbnb's overarching ESLint config](https://npmjs.com/eslint-config-airbnb)
 
 This entry point only errors on whitespace rules and sets all other rules to warnings. View the list of whitespace rules [here](https://github.com/airbnb/javascript/blob/master/packages/eslint-config-airbnb-base/whitespace.js).
 
+If using **flat config**, add `eslint-config-airbnb-base/whitespace-flat` to `eslint.config.mjs` / `eslint.config.cjs` / `eslint.config.js` :
+```js
+// eslint.config.cjs
+const whitespace = require('eslint-config-airbnb-base/whitespace-flat');
+
+module.exports = [
+  whitespace,
+  // ......
+];
+```
+
+```js
+// eslint.config.mjs
+import whitespace from 'eslint-config-airbnb-base/whitespace-flat';
+
+export default [
+  whitespace,
+  // ......
+];
+```
+
 ## Improving this config
 
 Consider adding test cases if you're making complicated rules changes, like anything involving regexes. Perhaps in a distant future, we could use literate programming to structure our README as test cases for our .eslintrc?

packages/eslint-config-airbnb-base/eslint.config.js

@@ -0,0 +1,12 @@
+module.exports = [
+  ...require('./flat'),
+  {
+    rules: {
+      // disable requiring trailing commas because it might be nice to revert to
+      // being JSON at some point, and I don't want to make big changes now.
+      "comma-dangle": 0,
+
+      "max-len": 0
+    }
+  }
+];

packages/eslint-config-airbnb-base/flat.js

@@ -0,0 +1,21 @@
+module.exports = [
+  ...([
+    './rules/flat/best-practices',
+    './rules/flat/errors',
+    './rules/flat/node',
+    './rules/flat/style',
+    './rules/flat/variables',
+    './rules/flat/es6',
+    './rules/flat/imports',
+    './rules/flat/strict',
+  ].reduce((p, c) => p.concat(require(c)), [])), // eslint-disable-line global-require, import/no-dynamic-require
+  {
+    languageOptions: {
+      parserOptions: {
+        ecmaVersion: 2018,
+        sourceType: 'module'
+      }
+    },
+    rules: {}
+  }
+];

packages/eslint-config-airbnb-base/package.json

@@ -5,8 +5,10 @@
   "main": "index.js",
   "exports": {
     ".": "./index.js",
+    "./flat": "./flat.js",
     "./legacy": "./legacy.js",
     "./whitespace": "./whitespace.js",
+    "./whitespace-flat": "./whitespace-flat.js",
     "./rules/best-practices": "./rules/best-practices.js",
     "./rules/es6": "./rules/es6.js",
     "./rules/node": "./rules/node.js",
@@ -15,6 +17,14 @@
     "./rules/imports": "./rules/imports.js",
     "./rules/strict": "./rules/strict.js",
     "./rules/variables": "./rules/variables.js",
+    "./rules/flat/best-practices": "./rules/flat/best-practices.js",
+    "./rules/flat/es6": "./rules/flat/es6.js",
+    "./rules/flat/node": "./rules/flat/node.js",
+    "./rules/flat/style": "./rules/flat/style.js",
+    "./rules/flat/errors": "./rules/flat/errors.js",
+    "./rules/flat/imports": "./rules/flat/imports.js",
+    "./rules/flat/strict": "./rules/flat/strict.js",
+    "./rules/flat/variables": "./rules/flat/variables.js",
     "./package.json": "./package.json"
   },
   "scripts": {
@@ -72,21 +82,22 @@
     "babel-preset-airbnb": "^4.5.0",
     "babel-tape-runner": "^3.0.0",
     "eclint": "^2.8.1",
-    "eslint": "^7.32.0 || ^8.2.0",
-    "eslint-find-rules": "^4.1.0",
+    "eslint": "^7.32.0 || ^8.2.0 || >= 9",
+    "eslint-find-rules": "^5.0.0",
     "eslint-plugin-import": "^2.30.0",
     "in-publish": "^2.0.1",
     "safe-publish-latest": "^2.0.0",
     "tape": "^5.9.0"
   },
   "peerDependencies": {
-    "eslint": "^7.32.0 || ^8.2.0",
+    "eslint": "^7.32.0 || ^8.2.0 || >= 9",
     "eslint-plugin-import": "^2.30.0"
   },
   "engines": {
     "node": "^10.12.0 || >=12.0.0"
   },
   "dependencies": {
-    "confusing-browser-globals": "^1.0.11"
+    "confusing-browser-globals": "^1.0.11",
+    "globals": "^15.14.0"
   }
 }

packages/eslint-config-airbnb-base/rules/flat/best-practices.js

@@ -0,0 +1,6 @@
+const baseConfig = require('../best-practices');
+
+module.exports = [{
+  name: 'eslint-config-airbnb-base/best-practices',
+  rules: baseConfig.rules
+}];

packages/eslint-config-airbnb-base/rules/flat/errors.js

@@ -0,0 +1,6 @@
+const baseConfig = require('../errors');
+
+module.exports = [{
+  name: 'eslint-config-airbnb-base/errors',
+  rules: baseConfig.rules
+}];

packages/eslint-config-airbnb-base/rules/flat/es6.js

@@ -0,0 +1,11 @@
+const globals = require('globals');
+const baseConfig = require('../es6');
+
+module.exports = [{
+  name: 'eslint-config-airbnb-base/es6',
+  languageOptions: {
+    globals: globals.es2015,
+    parserOptions: baseConfig.parserOptions
+  },
+  rules: baseConfig.rules
+}];

packages/eslint-config-airbnb-base/rules/flat/imports.js

@@ -0,0 +1,13 @@
+const importPlugin = require('eslint-plugin-import');
+const globals = require('globals');
+const baseConfig = require('../imports');
+
+module.exports = [importPlugin.flatConfigs.recommended, {
+  name: 'eslint-config-airbnb-base/imports',
+  languageOptions: {
+    globals: globals.es2015,
+    parserOptions: baseConfig.parserOptions
+  },
+  settings: baseConfig.settings,
+  rules: baseConfig.rules
+}];

packages/eslint-config-airbnb-base/rules/flat/node.js

@@ -0,0 +1,10 @@
+const globals = require('globals');
+const base = require('../node');
+
+module.exports = [{
+  name: 'eslint-config-airbnb-base/node',
+  languageOptions: {
+    globals: globals.node
+  },
+  rules: base.rules
+}];

packages/eslint-config-airbnb-base/rules/flat/strict.js

@@ -0,0 +1,6 @@
+const base = require('../strict');
+
+module.exports = [{
+  name: 'eslint-config-airbnb-base/strict',
+  rules: base.rules
+}];

packages/eslint-config-airbnb-base/rules/flat/style.js

@@ -0,0 +1,6 @@
+const base = require('../style');
+
+module.exports = [{
+  name: 'eslint-config-airbnb-base/style',
+  rules: base.rules
+}];

packages/eslint-config-airbnb-base/rules/flat/variables.js

@@ -0,0 +1,6 @@
+const base = require('../variables');
+
+module.exports = [{
+  name: 'eslint-config-airbnb-base/variables',
+  rules: base.rules
+}];

packages/eslint-config-airbnb-base/whitespace-flat-async.js

@@ -0,0 +1,49 @@
+#!/usr/bin/env node
+
+const { isArray } = Array;
+const { entries } = Object;
+const { ESLint } = require('eslint');
+
+const baseConfig = require('./flat');
+const whitespaceRules = require('./whitespaceRules');
+
+const severities = ['off', 'warn', 'error'];
+
+function getSeverity(ruleConfig) {
+  if (isArray(ruleConfig)) {
+    return getSeverity(ruleConfig[0]);
+  }
+  if (typeof ruleConfig === 'number') {
+    return severities[ruleConfig];
+  }
+  return ruleConfig;
+}
+
+async function onlyErrorOnRules(rulesToError, config) {
+  const errorsOnly = {
+    languageOptions: config[config.length - 1].languageOptions || {},
+    rules: config[config.length - 1].rules || {},
+  };
+  const cli = new ESLint({ baseConfig: config });
+  const baseRules = (await cli.calculateConfigForFile(require.resolve('./flat'))).rules;
+
+  entries(baseRules).forEach((rule) => {
+    const ruleName = rule[0];
+    const ruleConfig = rule[1];
+    const severity = getSeverity(ruleConfig);
+
+    if (rulesToError.indexOf(ruleName) === -1 && severity === 'error') {
+      if (isArray(ruleConfig)) {
+        errorsOnly.rules[ruleName] = ['warn'].concat(ruleConfig.slice(1));
+      } else if (typeof ruleConfig === 'number') {
+        errorsOnly.rules[ruleName] = 1;
+      } else {
+        errorsOnly.rules[ruleName] = 'warn';
+      }
+    }
+  });
+
+  return errorsOnly;
+}
+
+onlyErrorOnRules(whitespaceRules, baseConfig).then((config) => console.log(JSON.stringify(config)));

packages/eslint-config-airbnb-base/whitespace-flat.js

@@ -0,0 +1,13 @@
+/* eslint global-require: 0 */
+
+const path = require('path');
+const { execSync } = require('child_process');
+
+// NOTE: ESLint adds runtime statistics to the output (so it's no longer JSON) if TIMING is set
+module.exports = JSON.parse(String(execSync(path.join(__dirname, 'whitespace-flat-async.js'), {
+  cwd: __dirname, // NOTE: cwd is set to prevent ESLint.calculateConfigForFile return {}
+  env: {
+    ...process.env,
+    TIMING: undefined,
+  }
+})));

packages/eslint-config-airbnb/README.md

@@ -58,14 +58,79 @@ If you don't need React, see [eslint-config-airbnb-base](https://npmjs.com/eslin
 
 2. Add `"extends": "airbnb"` to your `.eslintrc`
 
+  If using **flat config**, add `eslint-config-airbnb/flat` to `eslint.config.mjs` / `eslint.config.cjs` / `eslint.config.js` :
+
+  ```js
+  // eslint.config.cjs
+  const airbnb = require('eslint-config-airbnb/flat');
+
+  module.exports = [
+    ...airbnb,
+    // ......
+  ];
+  ```
+
+  ```js
+  // eslint.config.mjs
+  import airbnb from 'eslint-config-airbnb/flat';
+
+  export default [
+    ...airbnb,
+    // ......
+  ];
+  ```
+
 ### eslint-config-airbnb/hooks
 
 This entry point enables the linting rules for React hooks (requires v16.8+). To use, add `"extends": ["airbnb", "airbnb/hooks"]` to your `.eslintrc`.
 
+If using **flat config**, add `eslint-config-airbnb/hooks-flat` to `eslint.config.mjs` / `eslint.config.cjs` / `eslint.config.js` :
+
+```js
+// eslint.config.cjs
+const hooksFlat = require('eslint-config-airbnb/hooks-flat');
+
+module.exports = [
+  ...hooksFlat,
+  // ......
+];
+```
+
+```js
+// eslint.config.mjs
+import hooksFlat from 'eslint-config-airbnb/hooks-flat';
+
+export default [
+  ...hooksFlat,
+  // ......
+];
+```
+
 ### eslint-config-airbnb/whitespace
 
 This entry point only errors on whitespace rules and sets all other rules to warnings. View the list of whitespace rules [here](https://github.com/airbnb/javascript/blob/master/packages/eslint-config-airbnb/whitespace.js).
 
+If using **flat config**, add `eslint-config-airbnb/whitespace-flat` to `eslint.config.mjs` / `eslint.config.cjs` / `eslint.config.js` :
+```js
+// eslint.config.cjs
+const whitespace = require('eslint-config-airbnb/whitespace-flat');
+
+module.exports = [
+  whitespace,
+  // ......
+];
+```
+
+```js
+// eslint.config.mjs
+import whitespace from 'eslint-config-airbnb/whitespace-flat';
+
+export default [
+  whitespace,
+  // ......
+];
+```
+
 ### eslint-config-airbnb/base
 
 This entry point is deprecated. See [eslint-config-airbnb-base](https://npmjs.com/eslint-config-airbnb-base).

packages/eslint-config-airbnb/eslint.config.js

@@ -0,0 +1,10 @@
+module.exports = [
+  ...require('./flat'), // eslint-disable-line global-require
+  {
+    rules: {
+      // disable requiring trailing commas because it might be nice to revert to
+      // being JSON at some point, and I don't want to make big changes now.
+      'comma-dangle': 0,
+    }
+  }
+];

packages/eslint-config-airbnb/flat.js

@@ -0,0 +1,8 @@
+module.exports = [
+  ...([
+    'eslint-config-airbnb-base/flat',
+    './rules/flat/react',
+    './rules/flat/react-a11y',
+  // eslint-disable-next-line global-require, import/no-dynamic-require
+  ].reduce((p, c) => p.concat(require(c)), []))
+];

packages/eslint-config-airbnb/hooks-flat.js

@@ -0,0 +1 @@
+module.exports = require('./rules/flat/react-hooks');