TypeScript Best Practices

TypeScript has become the standard for building large-scale JavaScript applications. Here are the best practices that will make your TypeScript code more robust and maintainable.

Type Safety

Avoid any

The any type defeats the purpose of TypeScript. Use unknown when you truly don't know the type.

// Bad
function process(data: any) {
  return data.value
}

// Good
function process(data: unknown) {
  if (typeof data === 'object' && data !== null && 'value' in data) {
    return data.value
  }
}

Utility Types

TypeScript provides powerful utility types. Use them!

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

type PartialUser = Partial<User>
type UserWithoutId = Omit<User, 'id'>
type ReadonlyUser = Readonly<User>

Discriminated Unions

Use discriminated unions for type-safe state management.

type LoadingState = { status: 'loading' }
type SuccessState = { status: 'success'; data: string }
type ErrorState = { status: 'error'; error: Error }

type State = LoadingState | SuccessState | ErrorState

Generic Constraints

Use generic constraints to make your functions more flexible yet type-safe.

Strict Mode

Always enable strict mode in your tsconfig.json. It catches many common errors.

TypeScript is a powerful tool, but only if you use it correctly. These practices will help you write better, safer code.