TypeScript Best Practices

Writing Better TypeScript Code

TypeScript adds powerful type checking to JavaScript, but using it effectively requires understanding best practices and common patterns.

Embrace Strong Typing

Avoid using 'any' whenever possible. Instead, create proper type definitions or use 'unknown' for truly unknown types:

// Bad
function process(data: any) { }

// Good
interface UserData {
  id: string
  name: string
}

function process(data: UserData) { }

Use Type Inference Wisely

TypeScript is smart about inferring types. Let it work for you instead of over-annotating:

// Over-annotated
const name: string = 'John'
const age: number = 30

// Better - let TypeScript infer
const name = 'John'
const age = 30

Discriminated Unions for State Management

Use discriminated unions to model complex state with type safety:

type State = 
  | { status: 'idle' }
  | { status: 'loading' }
  | { status: 'success', data: User[] }
  | { status: 'error', error: string }

Generic Constraints

Make your generic functions more type-safe with constraints:

function getProperty(obj: T, key: K) {
  return obj[key]
}

Utility Types

Leverage TypeScript's built-in utility types like Partial, Pick, Omit, and Record to transform types:

type User = {
  id: string
  name: string
  email: string
}

type UpdateUser = Partial
type UserPreview = Pick

Strict Mode Configuration

Enable strict mode in your tsconfig.json for maximum type safety. This catches more potential bugs at compile time.

Type Guards

Create type guard functions to safely narrow types at runtime:

function isUser(value: unknown): value is User {
  return typeof value === 'object' && 
         value !== null && 
         'id' in value
}

Following these practices leads to more maintainable, bug-free code. TypeScript's type system is powerful—use it to its full potential!