TypeScript Migration Guide

Incremental strategy for migrating JavaScript codebases to TypeScript. Designed for legacy projects that need progressive, non-disruptive migration.

When to Use This Skill

Activate when the user:

• Wants to convert a JS project (or parts of it) to TypeScript
• Needs to add TypeScript to an existing JavaScript project
• Asks about typing legacy code or reducing any usage
• Wants to improve type safety incrementally
• Is setting up tsconfig for a mixed JS/TS codebase

Core Principle: Incremental Migration

Never rewrite everything at once. Migrate file by file, starting from the leaves of the dependency tree. Every intermediate state must be a working codebase.