Migrate from ESLint

If you're using ESLint and want to switch to Ultracite's preconfigured setup, this guide will help you migrate while maintaining code quality standards.

Why Migrate to Ultracite?

• Lightning Speed: Biome (Ultracite's foundation) is based on Rust, much faster than ESLint
• Zero Configuration: Hundreds of preconfigured rules vs manual ESLint setup
• Combined Tool: Replaces both ESLint and Prettier with a single tool
• AI Integration: Built-in support for AI-powered editors (Cursor, Windsurf, GitHub Copilot)
• Type Safety: Comprehensive TypeScript rules with strict null checks
• Modern Standards: Latest JavaScript/TypeScript best practices

Before You Start

Make sure you have:

• An existing project using ESLint
• Node.js v14.18+ (Node 18+ recommended)
• A package.json file

Automatic Setup

Run the automatic setup script.

npx ultracite init

This will:

• Install Ultracite as a dependency
• Merge your existing biome.json / biome.jsonc with Ultracite's preset
• Merge your existing .vscode/settings.json with Ultracite's preset
• Enable strictNullChecks in your tsconfig.json file (or create one if it doesn't exist)
• Preserve your custom rules and settings
• Set up editor integrations

Ensure you choose to remove the existing ESLint configuration. This will:

• Remove ESLint and any related dependencies
• Remove any ESLint configuration files
• Remove any ESLint related commands from your .vscode/settings.json file

Following the upgrade, you may want to review your biome.json / biome.jsonc file to remove any overrides. Additionally, restart your editor to ensure the new configuration is applied.