TypeScript Learning Roadmap

Orient with the dual-audience mastery curriculum and keep the types encyclopedia open as a companion.

• How to Master TypeScript

  Stages, checkpoints, agent curls, and verification prompts for humans and AI agents

• Complete Types Reference

  Primitives, utilities, keyof/infer, mapped/conditional types, satisfies, const type params

• TypeScript 0 to Hero

  Introduction, installation, tsconfig setup, and compiling your first program

• Variance

  Covariance, contravariance, in/out annotations, readonly arrays as covariant

• Branded Types

  Opaque/branded types, nominal patterns, Zod brand, validation boundaries

Master the basics of static typing — annotations, inference, literals, and enums.

• Types & Annotations

  Primitive types, arrays, tuples, object types, union types, and explicit type annotations

• Type Inference

  How TypeScript infers types automatically, when to annotate explicitly, and best practices

• Literals & Unions

  Literal types, union types, discriminated unions, and narrowing with type guards

• Enums

  Numeric and string enums, const enums, reverse mappings, and when to use enums vs unions

Type functions properly, use overloads, and unlock the power of generics for reusable code.

• Function Types

  Function type annotations, return types, void, never, optional and default parameters

• Function Overloads

  Multiple overload signatures, implementation signatures, and when to use overloads vs unions

• Generics

  Generic functions, generic interfaces, constraints, defaults, and real-world generic patterns

Model complex data with interfaces, type aliases, and utility types.

• Interfaces

  Interface declarations, extending interfaces, merging declarations, and interface vs type

• Type Aliases

  The type keyword, intersection types, complex type compositions, and type-level programming

• Utility Types

  Partial, Required, Pick, Omit, Record, Readonly, ReturnType, Parameters, and built-in helpers

• never & unknown

  Top and bottom types, exhaustiveness checks, and safe handling of untrusted values

Apply TypeScript to OOP patterns and modular architecture.

• Classes

  Class syntax with TypeScript, typed properties, constructors, parameter properties, and methods

• Abstract Classes & Modifiers

  Abstract classes, access modifiers (public/private/protected), readonly, and static members

• Modules

  Resolution algorithms, path mapping, barrel exports

• Module Augmentation

  Declaration merging, module/global augmentation, ambient modules

• Iteration Protocols

  Iterable, iterator, async iteration, generators

Prove types through control flow and validate untrusted input at runtime.

• Narrowing

  Control flow analysis, type guards, assertion functions, discriminated unions

• Type Guards

  typeof, instanceof, in, custom type guards, and narrowing patterns

• satisfies Operator

  satisfies vs as — preserve inference while checking assignability

• Zod + TypeScript

  Runtime schemas, z.infer, API/env boundaries, branded types

• Branded Types

  Opaque types and nominal typing at validation boundaries

Conditional types, mapped types, template literals, variance, and design patterns.

• Conditional Types

  Conditional type logic, the infer keyword, distributive conditional types, and type-level branching

• Mapped Types

  Mapping over types with key remapping, adding/removing modifiers, and creating flexible transformations

• Template Literal Types

  Template literal types for string manipulation, type-safe event names, and SQL query types

• Variance

  Covariance/contravariance for functions, in/out annotations, readonly arrays

• Design Patterns

  Builder, Result/Either, exhaustive switches, DI typing, generic factories

Ship production-safe apps: strict flags, React patterns, ESLint, tests, monorepos, and migration.

• Strict Mode & Migration

  Enable strict flags one-by-one and migrate JavaScript to TypeScript safely

• JS→TS Migration Playbook

  allowJs, checkJs, gradual strict, converting CommonJS

• React + TypeScript

  Props, hooks typing, events, generic components, and context

• typescript-eslint

  Type-checked ESLint rules, ignores, and common fixes

• Testing with TypeScript

  Vitest + TS, typed mocks, Testing Library, assertion helpers

• tsconfig.json

  Compiler options, module resolution, paths, and recommended configs

• Declaration Files

  .d.ts files, ambient declarations, module augmentation, and DefinitelyTyped

• Project References

  Multi-package projects, incremental compilation, and monorepo TypeScript setup

• Monorepo TypeScript

  pnpm workspaces, project references deep dive, path mapping pitfalls

• Decorators

  Stage 3 decorators for classes and methods

• Best Practices

  Patterns, strict config habits, and code review checklist