TypeScript Best Practices for Large-Scale Applications

# TypeScript Best Practices

TypeScript has become the gold standard for building large-scale JavaScript applications. Here are the essential best practices that will help you write better, more maintainable code.

## Type Safety First

Always prioritize type safety over convenience:

```typescript
// Good
interface User {
id: string
email: string
name: string
createdAt: Date
}

// Avoid
const user: any = { ... }
```

## Advanced Type Patterns

### Utility Types

Leverage TypeScript's built-in utility types:

```typescript
type CreateUser = Omit
type UpdateUser = Partial>
```

### Generic Constraints

Use generic constraints for flexible yet safe APIs:

```typescript
interface Repository {
findById(id: string): Promise
create(data: Omit): Promise
update(id: string, data: Partial): Promise
}
```

## Project Structure

Organize your types effectively:

```
src/
types/
api.ts
user.ts
common.ts
utils/
type-guards.ts
validators.ts
```

## Error Handling

Implement robust error handling with discriminated unions:

```typescript
type ApiResponse =
| { success: true; data: T }
| { success: false; error: string }

async function fetchUser(id: string): Promise> {
try {
const user = await api.getUser(id)
return { success: true, data: user }
} catch (error) {
return { success: false, error: error.message }
}
}
```

## Conclusion

These practices will help you build more robust TypeScript applications that are easier to maintain and scale. Remember, the goal is to catch errors at compile time, not runtime.