ESLint

Pluggable linting for JavaScript and TypeScript.

Installation

bun add -D eslint @eslint/js typescript-eslint globals

Running ESLint

eslint . # Lint all files eslint --fix . # Auto-fix issues eslint src/file.ts # Specific file eslint --format json . # JSON output eslint --format stylish . # Styled output

Configuration (Flat Config - ESLint 9+)

eslint.config.js (Recommended)

import js from "@eslint/js"; import tseslint from "typescript-eslint"; import globals from "globals";

export default tseslint.config( js.configs.recommended, ...tseslint.configs.recommended, { languageOptions: { globals: { ...globals.node, ...globals.es2022, }, }, }, { ignores: ["dist/", "node_modules/", "*.config.js"], }, );

eslint.config.js (Strict TypeScript)

import js from "@eslint/js"; import tseslint from "typescript-eslint"; import globals from "globals";

export default tseslint.config( js.configs.recommended, ...tseslint.configs.strictTypeChecked, ...tseslint.configs.stylisticTypeChecked, { languageOptions: { globals: { ...globals.node, ...globals.es2022, }, parserOptions: { projectService: true, tsconfigRootDir: import.meta.dirname, }, }, }, { ignores: ["dist/", "node_modules/"], }, );

Common Rules

TypeScript Rules

{ rules: { "@typescript-eslint/no-unused-vars": ["error", { argsIgnorePattern: "^_" }], "@typescript-eslint/no-explicit-any": "warn", "@typescript-eslint/explicit-function-return-type": "off", "@typescript-eslint/no-floating-promises": "error", "@typescript-eslint/consistent-type-imports": ["warn", { prefer: "type-imports", fixStyle: "separate-type-imports" }], } }

JavaScript Rules

{ rules: { "no-console": ["warn", { allow: ["warn", "error"] }], "no-var": "warn", "no-unused-vars": ["error", { argsIgnorePattern: "^_" }], } }

File-Specific Configuration

export default tseslint.config( js.configs.recommended, ...tseslint.configs.recommended, { files: ["src//*.ts"], rules: { "@typescript-eslint/no-explicit-any": "error", }, }, { files: ["tests//*.ts"], rules: { "@typescript-eslint/no-explicit-any": "off", }, }, { ignores: ["dist/", "node_modules/"], }, );

Ignore Patterns

{ ignores: ["dist/", "node_modules/", "*.config.js", "coverage/", "build/"]; }

React Plugin

bun add -D eslint-plugin-react eslint-plugin-react-hooks eslint-plugin-react-refresh

import reactPlugin from "eslint-plugin-react"; import reactHooks from "eslint-plugin-react-hooks"; import reactRefresh from "eslint-plugin-react-refresh";

export default tseslint.config( // ...base config { plugins: { react: reactPlugin, "react-hooks": reactHooks, "react-refresh": reactRefresh, }, rules: { ...reactPlugin.configs.recommended.rules, ...reactHooks.configs.rules, "react-refresh/only-export-components": "warn", }, }, );

CI Integration

GitHub Actions

name: Lint on: [push, pull_request] jobs: eslint: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: oven-sh/setup-bun@v2 - run: bun install - run: bun run lint