@ansospace/eslint-config

Shared ESLint configuration for AnsoSpace projects with TypeScript, SonarJS, React, Next.js, and Node.js support.

Note: This package requires ESLint 9+ and uses the flat config format only. Legacy .eslintrc.js format is not supported.

Installation

npm install --save-dev @ansospace/eslint-config
# or
pnpm add -D @ansospace/eslint-config
# or
yarn add -D @ansospace/eslint-config

Features

• TypeScript Support: Full TypeScript linting with typescript-eslint
• Code Quality: SonarJS rules for bug detection and code smells
• React Support: React and React Hooks rules via react config
• Next.js Support: Next.js specific rules via next-js config
• Node.js/Express Support: Node.js and Express.js optimized config via node config
• Prettier Integration: Prevents conflicts with Prettier formatting
• Turbo Support: Optional Turbo-specific rules for Turborepo monorepos via turbo config

Configurations

Base Configuration

The base configuration includes TypeScript, SonarJS, and common rules. Use this for non-Turborepo projects.

// eslint.config.js (ESLint 9+ flat config)
import { baseConfig } from "@ansospace/eslint-config/base";

export default [...baseConfig];

Note: If you're in a Turborepo monorepo, you can add Turbo support on top of any config. See the Turborepo section below.

React Libraries

For React libraries and components:

import { reactConfig } from "@ansospace/eslint-config/react";

export default reactConfig;

Next.js Applications

For Next.js applications:

import { nextConfig } from "@ansospace/eslint-config/next-js";

export default nextConfig;

Node.js/Express.js Applications

For Node.js and Express.js backend applications:

import { nodeConfig } from "@ansospace/eslint-config/node";

export default [...nodeConfig];

Turborepo Monorepos

For Turborepo monorepos, you have two options:

Option 1: Use the turbo config directly

import { turboConfig } from "@ansospace/eslint-config/turbo";

export default turboConfig;

Option 2: Combine turbo config with framework-specific configs

For React projects in a Turborepo:

import { reactConfig } from "@ansospace/eslint-config/react";
import { turboConfig } from "@ansospace/eslint-config/turbo";

export default [...turboConfig, ...reactConfig];

For Next.js projects in a Turborepo:

import { nextConfig } from "@ansospace/eslint-config/next-js";
import { turboConfig } from "@ansospace/eslint-config/turbo";

export default [...turboConfig, ...nextConfig];

For Node.js projects in a Turborepo:

import { nodeConfig } from "@ansospace/eslint-config/node";
import { turboConfig } from "@ansospace/eslint-config/turbo";

export default [...turboConfig, ...nodeConfig];

What's Included

The node config includes:

• ✅ Node.js globals: process, Buffer, __dirname, etc.
• ✅ SonarJS: All recommended SonarJS rules for code quality
• ✅ TypeScript: Full TypeScript support with typescript-eslint
• ✅ Strict TypeScript rules: prefer-nullish-coalescing, strict-boolean-expressions
• ✅ Code style rules: prefer-template, prefer-arrow-callback, func-style, prefer-destructuring
• ✅ Express.js friendly defaults:
  • no-underscore-dangle: off (allows req._parsedUrl, etc.)
  • func-names: off (allows anonymous functions in routes)
  • no-console: error (strict by default, can be overridden)
  • indent: ["error", 2] (2-space indentation)

Express.js Example with Custom Rules

// eslint.config.js
import { nodeConfig } from "@ansospace/eslint-config/node";
import checkFile from "eslint-plugin-check-file";

export default [
  ...nodeConfig,
  {
    plugins: {
      "check-file": checkFile,
    },
    rules: {
      // File naming conventions (requires eslint-plugin-check-file)
      "check-file/filename-naming-convention": [
        "error",
        {
          "**/*.{ts,tsx}": "KEBAB_CASE",
        },
        {
          ignoreMiddleExtensions: true,
        },
      ],
      "check-file/folder-naming-convention": [
        "error",
        {
          "src/**/!^[.*": "KEBAB_CASE",
        },
      ],
      // Custom rules
      "max-len": ["error", { code: 100 }],
      "prefer-destructuring": [
        "error",
        {
          array: false,
          object: false,
        },
      ],
    },
  },
];

Migration from Legacy Config

If you're migrating from a legacy .eslintrc.js format:

Before (Legacy .eslintrc.js):

/** @type {import('eslint').Linter.Config} */
module.exports = {
  extends: ["@zurutech/eslint-config", "plugin:sonarjs/recommended-legacy"],
  parserOptions: { ecmaVersion: "latest", sourceType: "module" },
  plugins: ["sonarjs"],
  rules: {
    "no-console": "error",
    "func-names": ["error", "never"],
    // ... more rules
  },
};

After (ESLint 9+ Flat Config eslint.config.js):

import { nodeConfig } from "@ansospace/eslint-config/node";

export default [
  ...nodeConfig,
  {
    rules: {
      // Your custom rules
      "func-names": ["error", "never"],
      "max-len": ["error", { code: 100 }],
    },
  },
];

TypeScript Support in Node.js

For TypeScript files, the config automatically:

• Uses typescript-eslint parser
• Enables TypeScript-specific rules
• Uses tsconfig.eslint.json if available, falls back to tsconfig.json
• Allows require() in .ts files (with warning)
• Warns on any types (doesn't error)

Customizing Rules

You can override any rules in your eslint.config.js:

import { nodeConfig } from "@ansospace/eslint-config/node";

export default [
  ...nodeConfig,
  {
    rules: {
      // Override console.log to be an error
      "no-console": "error",
      // Custom max line length
      "max-len": ["error", { code: 120 }],
      // Disable specific SonarJS rule
      "sonarjs/cognitive-complexity": "off",
    },
  },
];

Ignored Files

The config automatically ignores:

• dist/**, build/**, node_modules/**
• **/.eslintrc.js, **/*.config.js, **/*.config.mjs
• **/*.md, eslint.config.mjs
• coverage**/*, *.history

Available Configurations

• base: Base configuration with TypeScript, SonarJS, and common rules
• react: For React libraries and components
• next-js: For Next.js applications
• node: For Node.js and Express.js backend applications
• turbo: For Turborepo monorepos (optional, only use if you have a turbo.json)

SonarJS Rules

All SonarJS recommended rules are enabled. Code quality rules are set to warnings to allow incremental improvement:

• sonarjs/cognitive-complexity: Warning (threshold: 15)
• sonarjs/no-nested-conditional: Warning
• sonarjs/no-duplicate-string: Warning
• sonarjs/no-identical-functions: Warning
• sonarjs/pseudo-random: Warning (for UI/non-critical contexts)
• sonarjs/no-commented-code: Warning
• sonarjs/no-small-switch: Warning
• sonarjs/no-redundant-boolean: Warning
• sonarjs/prefer-immediate-return: Warning

Critical bug detection and security rules remain as errors.

TypeScript Support

TypeScript is fully supported. The configuration:

• Uses typescript-eslint for TypeScript-specific rules
• Handles unused variables and parameters correctly
• Supports type definitions and function signatures
• Works with both .ts and .tsx files

License

MIT