feat: support both JavaScript and TypeScript linting

.eslintrc.json

@@ -1,19 +1,17 @@
 {
   "root": true,
-  "plugins": ["@typescript-eslint", "import", "promise", "unicorn"],
+  "plugins": ["import", "promise", "unicorn"],
   "env": {
     "browser": true,
     "node": true,
     "es2022": true
   },
-  "parser": "@typescript-eslint/parser",
   "parserOptions": {
     "ecmaVersion": 2022,
     "sourceType": "module",
     "ecmaFeatures": {
       "jsx": true
-    },
+    }
-    "project": "./tsconfig.json"
   },
   "rules": {
     "constructor-super": "error",
@@ -29,13 +27,11 @@
     "no-control-regex": "error",
     "no-debugger": "error",
     "no-dupe-args": "error",
-    "no-dupe-class-members": "off",
+    "no-dupe-class-members": "error",
-    "@typescript-eslint/no-dupe-class-members": "error",
     "no-dupe-else-if": "error",
     "no-dupe-keys": "error",
     "no-duplicate-case": "error",
-    "no-duplicate-imports": "off",
+    "no-duplicate-imports": "error",
-    "@typescript-eslint/no-duplicate-imports": "error",
     "no-empty-character-class": "error",
     "no-empty-pattern": "error",
     "no-ex-assign": "error",
@@ -44,8 +40,7 @@
     "no-import-assign": "error",
     "no-invalid-regexp": "error",
     "no-irregular-whitespace": "error",
-    "no-loss-of-precision": "off",
+    "no-loss-of-precision": "error",
-    "@typescript-eslint/no-loss-of-precision": "error",
     "no-misleading-character-class": "error",
     "no-new-symbol": "error",
     "no-obj-calls": "error",
@@ -64,17 +59,13 @@
     "no-unsafe-negation": "error",
     "no-unsafe-optional-chaining": "error",
     "no-unused-private-class-members": "error",
-    "no-unused-vars": "off",
+    "no-unused-vars": "error",
-    "@typescript-eslint/no-unused-vars": "error",
+    "no-use-before-define": [
-    "no-use-before-define": "off",
-    "@typescript-eslint/no-use-before-define": [
       "error",
       {
         "functions": false,
         "classes": false,
-        "enums": false,
+        "variables": false
-        "variables": false,
-        "typedefs": false
       }
     ],
     "no-useless-backreference": "error",
@@ -88,19 +79,16 @@
     "valid-typeof": ["error", { "requireStringLiterals": true }],
 
     "consistent-this": "error",
-    "default-param-last": "off",
+    "default-param-last": "error",
-    "@typescript-eslint/default-param-last": "error",
     "default-case-last": "error",
-    "dot-notation": "off",
+    "dot-notation": ["error", { "allowKeywords": true }],
-    "@typescript-eslint/dot-notation": ["error", { "allowKeywords": true }],
     "eqeqeq": ["error", "always", { "null": "ignore" }],
     "grouped-accessor-pairs": "error",
     "new-cap": [
       "error",
       { "newIsCap": true, "capIsNew": false, "properties": true }
     ],
-    "no-array-constructor": "off",
+    "no-array-constructor": "error",
-    "@typescript-eslint/no-array-constructor": "error",
     "no-caller": "error",
     "no-confusing-arrow": "error",
     "no-delete-var": "error",
@@ -108,8 +96,7 @@
     "no-eval": "error",
     "no-floating-decimal": "error",
     "no-global-assign": "error",
-    "no-implied-eval": "off",
+    "no-implied-eval": "error",
-    "@typescript-eslint/no-implied-eval": "error",
     "no-mixed-operators": [
       "error",
       {
@@ -127,15 +114,12 @@
     "no-octal": "error",
     "no-octal-escape": "error",
     "no-proto": "error",
-    "no-redeclare": "off",
+    "no-redeclare": ["error", { "builtinGlobals": false }],
-    "@typescript-eslint/no-redeclare": ["error", { "builtinGlobals": false }],
     "no-regex-spaces": "error",
     "no-shadow-restricted-names": "error",
-    "no-throw-literal": "off",
+    "no-throw-literal": "error",
-    "@typescript-eslint/no-throw-literal": "error",
     "no-undef-init": "error",
-    "no-unused-expressions": "off",
+    "no-unused-expressions": [
-    "@typescript-eslint/no-unused-expressions": [
       "error",
       {
         "allowShortCircuit": true,
@@ -145,8 +129,7 @@
     ],
     "no-useless-call": "error",
     "no-useless-computed-key": "error",
-    "no-useless-constructor": "off",
+    "no-useless-constructor": "error",
-    "@typescript-eslint/no-useless-constructor": "error",
     "no-useless-escape": "error",
     "no-useless-rename": "error",
     "no-useless-return": "error",
@@ -161,8 +144,7 @@
     "prefer-regex-literals": ["error", { "disallowRedundantWrapping": true }],
     "quote-props": ["error", "as-needed"],
     "radix": "error",
-    "require-await": "off",
+    "require-await": "error",
-    "@typescript-eslint/require-await": "error",
     "yoda": ["error", "never"],
 
     "import/no-absolute-path": "error",
@@ -200,8 +182,57 @@
   "overrides": [
     {
       "files": ["*.ts", "*.tsx"],
+      "parser": "@typescript-eslint/parser",
+      "plugins": ["@typescript-eslint"],
       "rules": {
         "no-undef": "off",
+        "no-dupe-class-members": "off",
+        "@typescript-eslint/no-dupe-class-members": "error",
+        "no-duplicate-imports": "off",
+        "@typescript-eslint/no-duplicate-imports": "error",
+        "no-loss-of-precision": "off",
+        "@typescript-eslint/no-loss-of-precision": "error",
+        "no-unused-vars": "off",
+        "@typescript-eslint/no-unused-vars": "error",
+        "no-use-before-define": "off",
+        "@typescript-eslint/no-use-before-define": [
+          "error",
+          {
+            "functions": false,
+            "classes": false,
+            "enums": false,
+            "variables": false,
+            "typedefs": false
+          }
+        ],
+        "default-param-last": "off",
+        "@typescript-eslint/default-param-last": "error",
+        "dot-notation": "off",
+        "@typescript-eslint/dot-notation": ["error", { "allowKeywords": true }],
+        "no-array-constructor": "off",
+        "@typescript-eslint/no-array-constructor": "error",
+        "no-implied-eval": "off",
+        "@typescript-eslint/no-implied-eval": "error",
+        "no-redeclare": "off",
+        "@typescript-eslint/no-redeclare": [
+          "error",
+          { "builtinGlobals": false }
+        ],
+        "no-throw-literal": "off",
+        "@typescript-eslint/no-throw-literal": "error",
+        "no-unused-expressions": "off",
+        "@typescript-eslint/no-unused-expressions": [
+          "error",
+          {
+            "allowShortCircuit": true,
+            "allowTernary": true,
+            "allowTaggedTemplates": true
+          }
+        ],
+        "no-useless-constructor": "off",
+        "@typescript-eslint/no-useless-constructor": "error",
+        "require-await": "off",
+        "@typescript-eslint/require-await": "error",
 
         "@typescript-eslint/adjacent-overload-signatures": "error",
         "@typescript-eslint/await-thenable": "error",

.github/workflows/lint.yml

@@ -2,7 +2,7 @@ name: 'Lint'
 
 on:
   push:
-    branches: [master, develop]
+    branches: [develop]
   pull_request:
     branches: [master, develop]
 

.github/workflows/test.yml

@@ -2,7 +2,7 @@ name: 'Test'
 
 on:
   push:
-    branches: [master, develop]
+    branches: [develop]
   pull_request:
     branches: [master, develop]
 

README.md

@@ -21,7 +21,7 @@
 
 ## 📜 About
 
-**eslint-config-conventions** is a [ESLint](https://eslint.org) configuration to enforce strict conventions and good code quality, it is highly inspired from [eslint-config-standard-with-typescript](https://github.com/standard/eslint-config-standard-with-typescript) but it is **stricter** and with **no formatting rules**, **only code-quality rules**.
+**eslint-config-conventions** is a [ESLint](https://eslint.org) configuration to enforce strict conventions and good code quality, it is highly inspired from [eslint-config-standard-with-typescript](https://github.com/standard/eslint-config-standard-with-typescript) but it is **stricter** and with **no formatting rules**, **only code-quality rules**. It supports both **JavaScript** and **TypeScript**.
 
 This configuration is mostly **for catching bugs** and **code-quality** so it is recommanded to use it with [Prettier](https://prettier.io/) for a consistent code style, it works with any `.prettierrc.json` configuration.
 
@@ -44,8 +44,6 @@ npm install --save-dev \
   eslint-plugin-import@^2.25.4 \
   eslint-plugin-promise@^6.0.0 \
   eslint-plugin-unicorn@^41.0.0 \
-  typescript@^4.4.0 \
-  @typescript-eslint/eslint-plugin@^5.12.0 \
   eslint-config-conventions@latest
 ```
 
@@ -58,9 +56,22 @@ This list of dependencies are:
   - [eslint-plugin-import](https://github.com/import-js/eslint-plugin-import)
   - [eslint-plugin-promise](https://github.com/xjamundx/eslint-plugin-promise)
   - [eslint-plugin-unicorn](https://github.com/sindresorhus/eslint-plugin-unicorn)
+- This package: `eslint-config-conventions`
+
+If you want to use **TypeScript**, you also need to install:
+
+```sh
+npm install --save-dev \
+  typescript@^4.4.0 \
+  @typescript-eslint/eslint-plugin@^5.12.0 \
+  @typescript-eslint/parser@^5.12.0
+```
+
+Dependencies are:
+
 - [TypeScript](https://github.com/Microsoft/TypeScript)
 - [@typescript-eslint/eslint-plugin](https://github.com/typescript-eslint/typescript-eslint); ESLint rules for TypeScript.
-- This package: `eslint-config-conventions`
+- [@typescript-eslint/parser](https://github.com/typescript-eslint/typescript-eslint); ESLint parser for TypeScript.
 
 ### Configuration with [Prettier](https://prettier.io/) (recommended)
 
@@ -91,7 +102,7 @@ echo {}> .prettierrc.json
 
 **Note:** Please read some important instructions regarding the `project` option [here](https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/parser/README.md#configuration).
 
-You must have a valid `tsconfig.json` file to specify `"parserOptions.project"`.
+`"parserOptions.project"` is only required if you use **TypeScript**.
 
 #### `package.json`
 

eslintrc.json

@@ -0,0 +1,6 @@
+{
+  "extends": "./index.js",
+  "parserOptions": {
+    "project": "./tsconfig.json"
+  }
+}

package-lock.json

@@ -35,12 +35,10 @@
         "npm": ">=8.0.0"
       },
       "peerDependencies": {
-        "@typescript-eslint/eslint-plugin": "^5.12.0",
         "eslint": "^8.9.0",
         "eslint-plugin-import": "^2.25.4",
         "eslint-plugin-promise": "^6.0.0",
-        "eslint-plugin-unicorn": "^41.0.0",
+        "eslint-plugin-unicorn": "^41.0.0"
-        "typescript": "^4.4.0"
       }
     },
     "node_modules/@babel/code-frame": {

package.json

@@ -31,7 +31,7 @@
     "lint:commit": "commitlint",
     "lint:editorconfig": "editorconfig-checker",
     "lint:markdown": "markdownlint \"**/*.md\" --dot --ignore-path \".gitignore\"",
-    "lint:javascript": "eslint \"**/*.{js,jsx,ts,tsx}\"",
+    "lint:javascript": "eslint \"**/*.{js,jsx,ts,tsx}\" -c \"eslintrc.json\"",
     "lint:prettier": "prettier \".\" --check --ignore-path \".gitignore\"",
     "lint:staged": "lint-staged",
     "test": "tape \"test/**/*.js\"",
@@ -44,9 +44,7 @@
     "eslint": "^8.9.0",
     "eslint-plugin-import": "^2.25.4",
     "eslint-plugin-promise": "^6.0.0",
-    "eslint-plugin-unicorn": "^41.0.0",
+    "eslint-plugin-unicorn": "^41.0.0"
-    "typescript": "^4.4.0",
-    "@typescript-eslint/eslint-plugin": "^5.12.0"
   },
   "devDependencies": {
     "@commitlint/cli": "16.2.1",

test/validate-config.js

@@ -1,8 +1,13 @@
 const { ESLint } = require('eslint')
 const test = require('tape')
 
+const eslint = new ESLint({
+  ignore: false,
+  useEslintrc: false,
+  overrideConfigFile: 'eslintrc.json'
+})
+
 test('ensure we validate correctly JavaScript files', async (t) => {
-  const eslint = new ESLint({ ignore: false })
   const [noErrors] = await eslint.lintFiles(
     'test/fixtures/javascript-no-errors.js'
   )
@@ -15,7 +20,6 @@ test('ensure we validate correctly JavaScript files', async (t) => {
 })
 
 test('ensure we validate correctly TypeScript files', async (t) => {
-  const eslint = new ESLint({ ignore: false })
   const [noErrors] = await eslint.lintFiles(
     'test/fixtures/typescript-no-errors.ts'
   )
@@ -28,7 +32,6 @@ test('ensure we validate correctly TypeScript files', async (t) => {
 })
 
 test('ensure we allow top-level await', async (t) => {
-  const eslint = new ESLint({ ignore: false })
   const [lintResult] = await eslint.lintFiles(
     'test/fixtures/top-level-await.mjs'
   )