typescript-advanced-types

# TypeScript Advanced Types Comprehensive guidance for mastering TypeScript's advanced type system including generics, conditional types, mapped types, template literal types, and utility types for building robust, type-safe applications. ## When to Use This Skill - Building type-safe libraries or frameworks - Creating reusable generic components - Implementing complex type inference logic - Designing type-safe API clients - Building form validation systems - Creating strongly-typed configuration objects - Implementing type-safe state management - Migrating JavaScript codebases to TypeScript ## Core Concepts ### 1. Generics **Purpose:** Create reusable, type-flexible components while maintaining type safety. **Basic Generic Function:** ```typescript function identity<T>(value: T): T { return value; } const num = identity<number>(42); // Type: number const str = identity<string>("hello"); // Type: string const auto = identity(true); // Type inferred: boolean ``` **Generic Constraints:** ```typescript interface HasLength { length: number; } function logLength<T extends HasLength>(item: T): T { console.log(item.length); return item; } logLength("hello"); // OK: string has length logLength([1, 2, 3]); // OK: array has length logLength({ length: 10 }); // OK: object has length // logLength(42); // Error: number has no length ``` **Multiple Type Parameters:** ```typescript function merge<T, U>(obj1: T, obj2: U): T & U { return { ...obj1, ...obj2...