Next Steps

What you can do now

• Install and run tsc
• Annotate primitives, interfaces, unions, and functions
• Narrow unions safely and avoid casual any
• Organize files with modules and a basic tsconfig

Practice ideas

Convert a small JavaScript script to TypeScript, add interfaces for your data, and turn on strict. Fix every error the compiler reports.

Common traps

• Using any to silence errors instead of modeling data
• Forgetting null checks on DOM queries
• Mismatching module settings between tsconfig and Node
• Editing emitted .js instead of the .ts source

Where to go next

• Deeper generics and conditional types
• Enums vs union literals
• Frontend frameworks with TypeScript (React, Vue, Svelte)
• API typing with zod or OpenAPI-generated clients
• Declaration files (.d.ts) for plain JavaScript libraries