Typescript Advanced Types

---
triggers:
  - "typescript advanced types"
name: typescript-advanced-types
description: Master TypeScript's advanced type system including generics, conditional types, mapped types, template literals, and utility types for building type-safe applications. Use when implementing complex type logic, creating reusable type utilities, or ensuring compile-time type safety in TypeScript projects.
---

# 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 {

## Note
Skill content truncated for token efficiency. Full version available in the source repository.