release: 0.99 breaking, switch to flat, package renamed back to eslint-config-coremail

ref https://eslint.org/docs/latest/use/configure/configuration-files-new

- breaking: switch to flat ESLint configuration
- breaking: package renamed back to eslint-config-coremail

Author: lwr

README.md

@@ -2,51 +2,45 @@
 # ESLint config files for Coremail (c)
 [![npm][npm-image]][npm-url]
 
-[npm-image]: https://img.shields.io/npm/v/eslint-plugin-coremail.svg
-[npm-url]: https://npmjs.org/package/eslint-plugin-coremail
-
-## Important Note
-
-Since eslint 6 changes its config resolving mechanism, config module can not share outside project root.
-
-<ins>**This project has been changed to a plugin module and renamed (only package name).**</ins>
-
-For more information, check this issue: https://github.com/eslint/eslint/issues/12654
+[npm-image]: https://img.shields.io/npm/v/eslint-config-coremail.svg
+[npm-url]: https://npmjs.org/package/eslint-config-coremail
 
 ## Usage
 
-To use this config, add this to your `package.json`
-
-```json
-{
-  "devDependencies"  : {
-    "eslint"                 : "8.46.0",
-    "eslint-plugin-coremail" : "0.5.0"
-  }
-}
-```
-
-or install manually
+This package exports [a flat ESLint configuration](https://eslint.org/blog/2022/08/new-config-system-part-2/)
+which is supported since `eslint 8.21.0`
 
 ```bash
-npm install eslint eslint-plugin-coremail
+npm install --save-dev eslint eslint-config-coremail
 ```
 
+Example `eslint.config.js` in esm:
+```js
+import {configs} from 'eslint-config-coremail';
+
+export default [
+    // default using browser & node env
+    configs.standard,
+    // for old IE compatible
+    {
+        files : ['path/to/legacy/**'],
+        ...configs.legacy,
+    },
+]
+```
 
-Then, add this to your `.eslintrc.yaml` file: 
-
-- Using standard rules
-
-    ```yaml
-    extends: plugin:coremail/standard
-    ```
-
-- Applying compliant rules (old IE compatible)
-
-    ```yaml
-    extends: plugin:coremail/compliant
-    ```
-
+Example `eslint.config.js` in commonjs:
+```js
+module.export = import('eslint-config-coremail').then(({configs}) => [
+    // default using browser & node env
+    configs.standard,
+    // for old IE compatible
+    {
+        files : ['path/to/legacy/**'],
+        ...configs.legacy,
+    },
+]);
+```
 
 ## Learn more
 

config/index.js

@@ -1,10 +1,16 @@
 /**
- * Copyright (c) 2020 Coremail.cn, Ltd. All Rights Reserved.
+ * Copyright (c) 2023 Coremail.cn, Ltd. All Rights Reserved.
  */
 
-module.exports = {
-    configs : {
-        standard  : require('./standard'),
-        compliant : require('./compliant'),
-    },
+import {use} from './util.js';
+import es from './standard.js';
+import es3 from './legacy.js';
+
+export {globals, use, mergeRules} from './util.js';
+export const configs = {
+    es,
+    node     : use(es, 'node'),
+    browser  : use(es, 'browser'),
+    standard : use(es, 'node', 'browser'),
+    legacy   : use(es3, 'builtin', 'browser'),
 };

config/compliant.js renamed to config/legacy.js

@@ -2,11 +2,15 @@
  * Copyright (c) 2023 Coremail.cn, Ltd. All Rights Reserved.
  */
 
-const error = 'error';
+import {error} from './util.js';
 
-module.exports = {
+export default {
 
-    parserOptions : {ecmaVersion : 3, allowReserved : true},
+    languageOptions : {
+        ecmaVersion   : 3,
+        sourceType    : 'script',
+        parserOptions : {allowReserved : true},
+    },
 
     rules : {
         /* eslint-disable indent *//* @formatter:off */

config/standard.js

@@ -2,15 +2,22 @@
  * Copyright (c) 2023 Coremail.cn, Ltd. All Rights Reserved.
  */
 
-const error = 'error', off = 'off', first = 'first', never = 'never';
+import standard from 'eslint-config-standard';
+import {error, first, mergeRules, never, off} from './util.js';
 
-module.exports = {
+export default {
 
-    extends       : ['standard'],
-    parserOptions : { ecmaVersion : 2024 },
+    languageOptions : {
+        ecmaVersion   : 'latest',
+        parserOptions : {ecmaFeatures : {jsx : true}},
+    },
+
+    plugins : Object.fromEntries(await Promise.all(standard.plugins.map(async key => [
+        key, (await import(`eslint-plugin-${key}`)).default,
+    ]))),
 
     /* eslint-disable indent */// @formatter:off
-    rules : {
+    rules : mergeRules(standard.rules, {
         'no-var'                        : [error],
         'no-tabs'                       : [error],
         'indent'                        : [error, 4, {
@@ -71,5 +78,8 @@ module.exports = {
         'no-empty'                      : [off],
         'n/no-path-concat'              : [off],
         'n/no-exports-assign'           : [off],
-    },
+
+        // waiting https://github.com/import-js/eslint-plugin-import/issues/2556
+        'import/export' : [off],
+    }),
 };

config/util.js

@@ -0,0 +1,72 @@
+/**
+ * Copyright (c) 2023 Coremail.cn, Ltd. All Rights Reserved.
+ */
+
+import {createRequire} from 'module';
+
+export const error = 'error', off = 'off', first = 'first', never = 'never';
+
+// try using 'globals' defined in the project first, it can be different between one required by eslint itself
+export const globals = (require => {
+    // projectDir (../../..)
+    //  +- node_modules (../..)
+    //      +- eslint
+    //      +- globals
+    //      +- eslint-config-email (..)
+    //          +- config (this location)
+    try {
+        // noinspection JSFileReferences
+        return require('../../../node_modules/globals');
+    } catch {
+        return require('globals');
+    }
+})(createRequire(import.meta.url));
+
+// merge configuration objects or env into one
+export function use(...envs) {
+    const result = {};
+    envs.forEach(x => Object.entries((typeof x === 'string') ? {globals : globals[x]} : x).forEach(([key, val]) => {
+        switch (key) {
+        case 'languageOptions':
+            const {globals, ...remains} = val;
+            result[key] = {...result[key], ...remains};
+            return addGlobals(result, globals);
+
+        case 'globals':
+            return addGlobals(result, val);
+
+        case 'rules':
+            return (result[key] = mergeRules(result[key], val));
+
+        case 'linterOptions':
+        case 'plugins':
+        case 'settings':
+            return (result[key] = {...result[key], ...val});
+        }
+        result[key] = val;
+    }));
+    return result;
+}
+
+function addGlobals(x, globals) {
+    const languageOptions = x.languageOptions = (x.languageOptions || {});
+    languageOptions.globals = {...x.languageOptions.globals, ...globals};
+}
+
+
+// ref https://eslint.org/docs/latest/use/configure/configuration-files-new#rule-configuration-cascade
+// cascaded rules only override severity if passing in a simple value
+export function mergeRules(...rules) {
+    const result = {};
+    rules.forEach(rules => Object.entries(rules || {}).forEach(([ruleId, def]) => {
+        if (Array.isArray(result[ruleId])) {
+            if (typeof def === 'string') {
+                return (result[ruleId][0] = def);
+            } else if (def?.length === 1 && typeof def?.[0] === 'string') {
+                return (result[ruleId][0] = def[0]);
+            }
+        }
+        result[ruleId] = def;
+    }));
+    return result;
+}

eslint.config.js

@@ -0,0 +1,21 @@
+// noinspection JSUnusedGlobalSymbols
+
+import {configs} from './config/index.js';
+
+export default [configs.es, {
+    files : ['test/samples/**'],
+    rules : {
+        // disable debatable rules
+        'semi'   : 'off',
+        'quotes' : 'off',
+        // sample test codes have many unused / undeclared symbols
+        'no-undef'              : 'off',
+        'no-unused-vars'        : 'off',
+        'no-unreachable'        : 'off',
+        'no-constant-condition' : 'off',
+        'no-use-before-define'  : 'off',
+    },
+}, {
+    files : ['test/samples/es3/**'],
+    ...configs.legacy,
+}];

package.json

@@ -1,12 +1,14 @@
 {
-  "name"             : "eslint-plugin-coremail",
+  "name"             : "eslint-config-coremail",
   "description"      : "Javascript Standard Style - ESLint Shareable Config for coremail.cn",
-  "version"          : "0.5.0",
+  "version"          : "0.99.1",
   "author"           : {
     "name"  : "William Leung",
     "email" : "[email protected]"
   },
 
+  "type"             : "module",
+
   "keywords"         : [
     "code linter",
     "code sytle",
@@ -22,28 +24,24 @@
 
   "license"          : "MIT",
   "main"             : "config/index.js",
+  "files"            : [
+    "config/*"
+  ],
 
   "scripts"          : {
     "test" : "eslint ."
   },
 
   "peerDependencies" : {
-    "eslint" : "^8.46.0"
+    "eslint"  : "^8.52.0",
+    "globals" : "*"
   },
 
   "devDependencies"  : {
-    "eslint" : "~8.46.0"
+    "eslint" : "~8.52.0"
   },
 
   "dependencies"     : {
-    "eslint-plugin-promise"  : "~6.1.1",
-    "eslint-plugin-import"   : "~2.28.0",
-    "eslint-plugin-node"     : "~11.1.0",
     "eslint-config-standard" : "~17.1.0"
-  },
-
-  "eslintConfig"     : {
-    "root"    : true,
-    "extends" : "./config/standard.js"
   }
 }