Migrating from JavaScript to TypeScript: Why and How

The Problem TypeScript Solves

JavaScript is dynamically typed — a variable's type is only known at runtime. That flexibility is fine for small projects, but on larger ones it means bugs that should have been caught during development instead surface in production. TypeScript adds a type system on top of JavaScript, catching many of these errors the moment you write the code.

Migrate Gradually, Not Overnight

The good news: you don't need to convert your whole project overnight. TypeScript is designed to work alongside .js files. Just name new files .ts or .tsx, and migrate older files over time.

Where to Start

• Begin with a lenient tsconfig.json (strict: false).
• Migrate data models and utility functions first — they give the best return on investment.
• Eventually turn on strict: true to get the full benefit of TypeScript.

Takeaway

Migrating to TypeScript is an investment that clearly pays off on long-lived projects, in the form of fewer bugs and more confidence when refactoring.