Chapter 45: TypeScript Study Plan
TypeScript Study Plan written exactly as if I am your personal mentor sitting next to you in Hyderabad, explaining how a serious developer should actually learn TypeScript in 2025–2026 so that it becomes a real superpower in your daily work — not just another certificate.
This plan assumes:
- You already know modern JavaScript reasonably well (ES6+, async/await, modules, destructuring, array methods…)
- You want to reach production confidence (able to work in medium/large teams, contribute to typed libraries, feel safe refactoring, interview well)
- You can invest 5–12 hours per week (adjust speed accordingly)
Total realistic timeline: 4–12 months depending on starting point and weekly hours.
Phase 0 – Before you start (1–2 weeks max)
Goal — avoid 90 % of beginner frustration
Must-have foundations (quick self-check):
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// If you can instantly understand & improve these, skip to Phase 1 const data = { name: "Sara", age: 28 }; const { name, ...rest } = data; async function fetchUser() { const res = await fetch("/api/user"); return res.ok ? await res.json() : null; } const doubled = [1,2,3].map(x => x * 2); function greet({ name = "Guest", age }) { return `Hello ${name}${age ? ` (${age})` : ""}`; } |
If any line feels uncomfortable → spend 1–2 weeks on modern JavaScript first (MDN, JavaScript.info, freeCodeCamp JS section).
Phase 1 – TypeScript Survival Kit (3–6 weeks)
Goal — Understand what TS actually does (and does not) at runtime + write your first useful typed code
Key topics & order (do not skip order):
- What is TypeScript really? (type layer only, no runtime cost, tsc output)
- Installation & first tsconfig (tsc –init, allowJs, checkJs, noEmit)
- Basic annotations & inference
- Union & literal types + as const
- Objects: interface vs type
- Arrays & tuples
- Functions (parameters, return types, optional/default)
- Type narrowing basics (typeof, ===, == null)
- null / undefined / optional chaining / nullish coalescing
- unknown vs any in catch blocks
Success criteria after Phase 1 You should be able to write & understand code like this without hesitation:
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type Size = "xs" | "sm" | "md" | "lg" | "xl"; const sizes = { xs: "0.5rem", sm: "0.75rem", md: "1rem" } as const satisfies Record<Size, string>; function getPadding(size: Size): string { return sizes[size]; } // Now try wrong value → instant red squiggle // getPadding("xxxl") |
Recommended resources for Phase 1
- Official Handbook – The Basics + Everyday Types
- TypeScript for JavaScript Programmers (typescriptlang.org)
- 3–5 short YouTube videos: Basarat → “TypeScript in 100 seconds”, “TypeScript Basics”
Phase 2 – Everyday Safety & Productivity (6–10 weeks)
Goal — Reach the level where most junior-mid developers live in real projects
Key topics:
- Strict mode flags (start turning them on one by one)
- Generics basics + extends constraints
- Utility types you actually use daily (Partial, Pick, Omit, Record, ReturnType, Parameters, Awaited)
- satisfies operator (use it everywhere possible)
- Custom type guards (is predicates)
- Discriminated unions + exhaustive checks
- unknown in catch + proper narrowing
- Branded types / nominal typing for IDs, emails, slugs
Success criteria after Phase 2
You should comfortably write patterns like:
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type Result<T, E = Error> = | { success: true; data: T } | { success: false; error: E }; async function fetchUser(id: string): Promise<Result<User>> { try { // ... } catch (err: unknown) { return { success: false, error: err instanceof Error ? err : new Error("Unknown") }; } } |
and feel confident narrowing in components, hooks, API layers.
Phase 3 – Advanced Types & Architecture (8–16 weeks)
Goal — Start thinking like a TypeScript library author or senior engineer
Key topics:
- Conditional types + infer
- Mapped types + key remapping (as clause)
- Template literal types
- Recursive types (DeepPartial, Paths, Mutable)
- Declaration merging & module augmentation
- Generic components / hooks in React
- Advanced utility patterns (UnionToIntersection, OmitThisParameter, etc.)
Success criteria after Phase 3
You should be able to build / understand:
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type Paths<T> = /* deep key paths union */ type DeepReadonly<T> = /* recursive readonly */ type ExtractRouteParams<T extends string> = /* ":id" → "id" */ |
Phase 4 – Tooling, Ecosystem, Frameworks (ongoing – parallel to Phase 3)
Key topics:
- tsconfig mastery (paths, bundler vs nodenext, isolatedModules, verbatimModuleSyntax…)
- ESLint + typescript-eslint recommended rules
- Vite / Next.js / Node.js specific configs
- React + TS patterns (hooks, context, generics, forwardRef…)
- tRPC / Zod / TanStack Query typing patterns
- Publishing typed NPM packages (.d.ts, types field, dual CJS/ESM)
Phase 5 – Mastery & Library-level Thinking (6–18 months in)
- Writing your own utility types
- Branded types + opaque types
- Advanced inference tricks
- Contributing to DefinitelyTyped or open-source TS libraries
- Performance debugging of complex types
- Teaching / writing blog posts about TS
Weekly rhythm that actually works
- Mon–Fri: 45–90 min theory + 1–3 exercises
- Weekend: refactor/refactor one real file in your project using new concepts
- Every 2 weeks: solve 10 quiz questions
- Every 4–6 weeks: build one small typed mini-project (CLI tool, React component library, API client, form validator…)
Where are you right now? (quick self-check)
- I barely know JS modules / async → Phase 0–1
- I can use : string but union / narrowing confuses me → Phase 1–2
- I use TS daily but avoid generics / advanced types → Phase 2–3
- I already use generics & utilities but want to go deep → Phase 3–4
- I want to contribute libraries / become team TS expert → Phase 4–5
Tell me roughly where you feel you are + how many hours/week you can invest → I’ll give you the next 5–7 concrete exercises / topics that will give you the biggest jump right now 😄
