TypeScript Best Practices for 2024

Note: This is mock/placeholder content for demonstration purposes.

TypeScript has become the de facto standard for building large-scale JavaScript applications. Here are some best practices to help you write better TypeScript code.

1. Use Strict Mode

Always enable strict mode in your . This catches more errors at compile time and forces you to write more explicit code.

{
  "compilerOptions": {
    "strict": true
  }
}

2. Prefer Type Inference

Let TypeScript infer types when possible. Don't over-annotate your code.

// Over-annotated
const name: string = "John";
const numbers: number[] = [1, 2, 3];

// Let TypeScript infer
const name = "John";
const numbers = [1, 2, 3];

3. Use Union Types and Type Guards

Union types are powerful for representing values that could be one of several types.

type Result<T> = { success: true; data: T } | { success: false; error: string };

function handleResult<T>(result: Result<T>) {
  if (result.success) {
    console.log(result.data);
  } else {
    console.error(result.error);
  }
}

4. Leverage Utility Types

TypeScript provides many built-in utility types that can save you time and make your code more expressive.

interface User {
  id: string;
  name: string;
  email: string;
  createdAt: Date;
}

// Make all properties optional
type PartialUser = Partial<User>;

// Make all properties required
type RequiredUser = Required<User>;

// Pick specific properties
type UserCredentials = Pick<User, 'email' | 'name'>;

// Omit specific properties
type PublicUser = Omit<User, 'email'>;

5. Use Const Assertions

Const assertions help you create more specific types from literal values.

// Without const assertion - type is string[]
const colors = ['red', 'green', 'blue'];

// With const assertion - type is readonly ['red', 'green', 'blue']
const colors = ['red', 'green', 'blue'] as const;

6. Define Clear API Boundaries

Use interfaces for objects and types for unions, primitives, and complex types.

// Use interface for objects
interface ApiResponse {
  data: unknown;
  status: number;
}

// Use type for unions and complex types
type Status = 'pending' | 'fulfilled' | 'rejected';
type Callback<T> = (value: T) => void;

7. Handle Null and Undefined Properly

Use optional chaining and nullish coalescing to handle null and undefined values safely.

interface User {
  address?: {
    street?: string;
  };
}

// Optional chaining
const street = user?.address?.street;

// Nullish coalescing
const displayName = user.name ?? 'Anonymous';

Conclusion

Following these TypeScript best practices will help you write more maintainable, type-safe code. Remember that TypeScript is a tool to help you catch errors early and improve your development experience.

Keep learning and improving your TypeScript skills!