Core Types
Types vs Interfaces — Complete Interview Guide
Master the real differences between type aliases and interfaces in TypeScript — when to use each, how declaration merging works, which extends which, and how to answer every interviewer question on this perennial topic with confidence.
Generics — Complete Interview Guide
Deep-dive into TypeScript generics — type parameters, constraints, default types, generic functions, interfaces, and classes.
Type Guards & Narrowing — Complete Interview Guide
Understand TypeScript's type narrowing system — typeof, instanceof, in operator, discriminated unions, custom type predicates, and the never type for exhaustive checks.
Union & Intersection Types — Complete Interview Guide
Master TypeScript union and intersection types — how | and & work, discriminated unions for safe branching, structural composition with intersections, and the real semantic difference between OR-typed and AND-typed shapes.
Enums — Complete Interview Guide
Understand TypeScript enums thoroughly — numeric, string, and const enums, their runtime representation, when to use them versus union literal types, and the gotchas that trip up even experienced TypeScript developers.
Built-in Types
OOP
Advanced Types
Mapped Types — Complete Interview Guide
Master TypeScript's mapped types — how they iterate over keys to transform type shapes, modifier addition and removal, key remapping with as, and how every built-in utility type (Partial, Required, Readonly, Pick) is implemented with them.
Conditional Types — Complete Interview Guide
Deep-dive into TypeScript conditional types — the T extends U ? X : Y syntax, distributive behaviour over unions, the infer keyword for type extraction, and how to build powerful type utilities like ReturnType, Awaited, and NonNullable from first principles.
Decorators — Complete Interview Guide
Deep-dive into TypeScript decorators — class, method, property, accessor, and parameter decorators.