ESLint to Biome Migration Blueprint

Overview of this Migration Scenario

Migrating from ESLint and Prettier to Biome represents a significant shift in how linting and formatting are handled in your JavaScript and TypeScript projects. Biome is a modern tool that combines linting, formatting, and TypeScript support into a single, cohesive experience. This migration can enhance productivity by streamlining your development workflow and reducing configuration overhead.

Prerequisites and Planning Requirements

Before initiating the migration, ensure you have the following prerequisites in place:

Node.js: Ensure you have Node.js installed, as Biome requires it to run.
Existing ESLint and Prettier Configurations: Understand your current ESLint and Prettier setup, including rules, plugins, and configuration files.
Backup: Create a backup of your existing project to safeguard against any issues during migration.
Team Communication: Inform your team about the migration timeline and expectations, especially if they rely heavily on the current linting setup.

Phase-by-Phase Implementation Guide

Phase 1: Assessment

Evaluate Current Setup: Review ESLint and Prettier configurations. Document all custom rules and plugins used.
Identify Gaps: Compare the features of ESLint/Prettier with Biome to identify any potential gaps or rules that may not translate directly.

Phase 2: Configuration Setup

Install Biome: Run the following command to install Biome in your project:
```
npm install --save-dev biome
```
Create Configuration File: Create a .biome.json configuration file in your project root. Here’s a basic example:
```
{
  "lint": {
    "rules": {
      "semi": "error",
      "quotes": ["error", "single"]
    }
  }
}
```
Migrate Rules: Carefully translate your ESLint rules into the Biome configuration, checking the Biome documentation for equivalent rule formats.

Phase 3: Testing and Validation

Run Linting: Execute Biome linting on your codebase:
```
npx biome lint
```
Fix Issues: Address any linting errors that arise. Biome will provide suggestions and fixes similar to ESLint.

Phase 4: Integration

Integrate with Build Process: Ensure that Biome is integrated into your CI/CD pipeline to enforce linting during the build process.
Update Scripts: Update your project’s package.json scripts to replace ESLint and Prettier commands with Biome:
```
"scripts": {
  "lint": "biome lint",
  "format": "biome format"
}
```

Phase 5: Final Review

Team Review: Conduct a team review of the new setup to ensure everyone is comfortable with the new tooling.
Feedback Loop: Set up a feedback loop for ongoing improvements and adjustments.

Key Decision Points and Considerations

Rule Compatibility: Determine if all necessary ESLint rules have a direct equivalent in Biome.
Team Training: Assess whether team members need training on the new tool and its features.
Performance: Monitor performance and usability post-migration to identify areas for further optimization.

Testing and Validation Strategies

Automated Testing: Implement automated tests to ensure the migration didn’t introduce any errors in code quality.
Code Reviews: Establish a code review process specifically for linting and formatting to ensure compliance with the new rules.
Continuous Feedback: Use developer feedback to refine configurations and rules over time.

Common Challenges and Solutions

Rule Differences: Some ESLint rules may not have direct equivalents in Biome, requiring custom solutions or rule adjustments.
- Solution: Create custom rules or adjust your development practices to accommodate the differences.
Team Resistance: Some team members may be resistant to change.
- Solution: Highlight the benefits of Biome and involve team members in the migration process to increase buy-in.

Post-Migration Checklist and Optimization

Verify all linting and formatting rules are functioning as intended.
Ensure CI/CD integration is seamless and catches errors during builds.
Gather team feedback on the new setup and make necessary adjustments.
Regularly update Biome to take advantage of new features and improvements.
Document the migration process for future reference and onboarding.

By following this blueprint, you can ensure a smooth transition from ESLint/Prettier to Biome, enhancing your team's efficiency and code quality in the long term.

ESLint to Biome Blueprint