Module 7 — Working with Existing JavaScript Codebases

Transition from JavaScript to TypeScript smoothly. Learn about handling any type, interoperability, and migration best practices.

📄️Migrating JavaScript to TypeScript

Learn how to safely migrate JavaScript to TypeScript using allowJs, checkJs, JSDoc, and incremental file conversion strategies.

📄️Interoperability

Discover how to type untyped npm packages and legacy JS modules. Learn the difference between JSDoc and declaration files for a gradual TypeScript adoption.

📄️Handling 'any' in Legacy Code

Stop the spread of 'any'. Learn to use type boundaries, generics, and JSDoc to gradually improve type safety in JavaScript and legacy TypeScript projects.

📄️Hands‑On Exercise: Migrate a Small JS Module to TS with Minimal Friction

Learn how to safely convert legacy JavaScript modules to TypeScript. This hands-on exercise covers JSDoc types, tsconfig setup, and incremental TS adoption.

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Migrating JavaScript to TypeScript