Advanced TypeScript Patterns for Better Code

TypeScript's type system is incredibly powerful. Let's explore some advanced patterns that can improve your code quality.

Conditional Types

Create types that change based on conditions:

type ApiResponse<T> = T extends string 
  ? { message: T } 
  : { data: T }

type StringResponse = ApiResponse<string> // { message: string }
type DataResponse = ApiResponse<User[]>   // { data: User[] }

Mapped Types

Transform existing types:

type Partial<T> = {
  [P in keyof T]?: T[P]
}

type Required<T> = {
  [P in keyof T]-?: T[P]
}

Template Literal Types

Create string types with patterns:

type EventName<T extends string> = `on${Capitalize<T>}`

type ButtonEvents = EventName<'click' | 'hover'> // 'onClick' | 'onHover'

Utility Types in Practice

Combine utility types for powerful patterns:

interface User {
  id: number
  name: string
  email: string
  password: string
}

type PublicUser = Omit<User, 'password'>
type CreateUser = Omit<User, 'id'>
type UpdateUser = Partial<CreateUser>

These patterns help create more maintainable and type-safe applications.