Why TypeScript?
TypeScript adds a type system on top of JavaScript, catching bugs at compile time rather than runtime. Studies consistently show it reduces production bugs by 15-30%. If you write JavaScript professionally, learning TypeScript is the highest-leverage skill investment you can make this year.
Week 1: Fundamentals
Start by understanding the core type system.
- Day 1-2: Install TypeScript (npm i -g typescript), create tsconfig.json, and compile your first program.
- Day 3-4: Learn primitive types — string, number, boolean, null, undefined, symbol, bigint.
- Day 5-6: Master arrays and object types. Write interfaces and type aliases.
- Day 7: Practice union types and type narrowing with typeof guards.
Week 2: Generics and Advanced Types
Generics are where TypeScript's real power emerges. They let you write reusable, type-safe code.
- Day 8-9: Learn generics syntax and use generic constraints with extends.
- Day 10-11: Understand utility types — Partial, Required, Readonly, Pick, Omit, Record.
- Day 12-13: Master conditional types and mapped types.
- Day 14: Learn the keyof operator and index signatures.
Week 3: Real-World Patterns
- Day 15-16: Set up a Next.js or Vite project with strict mode enabled.
- Day 17-18: Learn to type API responses, form data, and localStorage.
- Day 19-20: Explore Zod for runtime validation with inferred TypeScript types.
- Day 21: Add ESLint with the TypeScript plugin.
Week 4: Advanced Mastery
- Day 22-23: Master the infer keyword in conditional types.
- Day 24-25: Learn declaration files (.d.ts) and module augmentation.
- Day 26-27: Explore branded/nominal types for domain modeling.
- Day 28-30: Set up project references for monorepos and contribute to an open-source TypeScript project.
Conclusion
TypeScript is becoming the standard for professional JavaScript development. The 30-day roadmap above gives you a structured path from beginner to confident user. The investment pays dividends in every project you touch afterward.