---

name: eslint description: Lints JavaScript and TypeScript code, configures rules, and fixes issues automatically. Use when linting code, fixing style issues, configuring eslint.config.js, or enforcing code quality standards.

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