TypeScript Best Practices for Large Applications

TypeScript for Large Projects

Scale your TypeScript codebase with these best practices.

Strict Mode

// tsconfig.json
{
  "compilerOptions": {
    "strict": true,
    "noImplicitAny": true,
    "strictNullChecks": true
  }
}

Use Interfaces for Objects

interface User {
  id: number;
  name: string;
  email: string;
  role: 'admin' | 'user';
}

// Extend interfaces
interface AdminUser extends User {
  permissions: string[];
}

Type vs Interface

• Use interface for object shapes
• Use type for unions, primitives, tuples

Avoid 'any'

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

// Good
function process(data: unknown) {
  if (typeof data === 'string') {
    // Now TypeScript knows it's a string
  }
}

Utility Types

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

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

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

// Omit properties
type UserWithoutId = Omit<User, 'id'>;

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