Writing Robust TypeScript at Scale

TypeScript is essential for large-scale JavaScript applications. However, simply adding types isn't enough. You need patterns that scale.

1. Avoid any at All Costs

Using any defeats the purpose of TypeScript. Use unknown if you truly don't know the type, and then narrow it down.

2. Use Utility Types

Leverage built-in mapped types to keep your code DRY.

• Partial<T>: Makes all properties optional.
• Pick<T, K>: Selects a subset of properties.
• Omit<T, K>: Removes specific properties.

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

// Update DTO needs only editable fields
type UpdateUserDto = Partial<Omit<User, 'id'>>;

3. Zod for Runtime Validation

TypeScript types disappear at runtime. Use Zod to validate external data (APIs, forms) and infer types automatically.

import { z } from 'zod';

const UserSchema = z.object({
  username: z.string().min(3),
  email: z.string().email(),
});

type User = z.infer<typeof UserSchema>;

Conclusion

Strict TypeScript configs and runtime validation with Zod create a bulletproof codebase that is easy to refactor.

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