Building Robust Applications with TypeScript
TypeScript has revolutionized how we write JavaScript, bringing type safety and enhanced developer experience to modern web development. However, to truly harness its power, you need to follow established best practices that ensure your code is maintainable, scalable, and robust.
Essential TypeScript Configuration
Strict Mode Configuration
Always start with a strict TypeScript configuration to catch potential issues early:
{
"compilerOptions": {
"strict": true,
"noImplicitAny": true,
"strictNullChecks": true,
"strictFunctionTypes": true,
"noImplicitReturns": true,
"noFallthroughCasesInSwitch": true,
"noUncheckedIndexedAccess": true
}
}
Path Mapping for Clean Imports
Configure path mapping to avoid relative import hell:
{
"compilerOptions": {
"baseUrl": ".",
"paths": {
"@/*": ["src/*"],
"@/components/*": ["src/components/*"],
"@/utils/*": ["src/utils/*"],
"@/types/*": ["src/types/*"]
}
}
}
Type Definition Best Practices
1. Use Interfaces for Object Shapes
// β
Good: Clear interface definition
interface User {
readonly id: string;
name: string;
email: string;
createdAt: Date;
preferences?: UserPreferences;
}
interface UserPreferences {
theme: 'light' | 'dark';
notifications: boolean;
language: string;
}
2. Leverage Union Types for Flexibility
// β
Good: Descriptive union types
type Status = 'pending' | 'approved' | 'rejected';
type Theme = 'light' | 'dark' | 'auto';
// β
Good: Discriminated unions
type ApiResponse<T> =
| { success: true; data: T }
| { success: false; error: string };
3. Use Generic Types for Reusability
// β
Good: Reusable generic interface
interface ApiClient<T> {
get(id: string): Promise<T>;
create(data: Omit<T, 'id'>): Promise<T>;
update(id: string, data: Partial<T>): Promise<T>;
delete(id: string): Promise<void>;
}
// Usage
const userClient: ApiClient<User> = new UserApiClient();
const postClient: ApiClient<Post> = new PostApiClient();
Advanced Type Patterns
1. Utility Types for Transformation
// β Good: Using utility types type CreateUserRequest = Omit<User, 'id' | 'createdAt'>; type UpdateUserRequest = Partial<Pick<User, 'name' | 'email'>>; type UserSummary = Pick<User, 'id' | 'name' | 'email'>;
2. Conditional Types for Complex Logic
// β
Good: Conditional types for API responses
type ApiEndpoint<T extends string> = T extends `${infer Method} ${infer Path}`
? Method extends 'GET'
? { method: 'GET'; path: Path; body?: never }
: { method: Method; path: Path; body: unknown }
: never;
type GetUsers = ApiEndpoint<'GET /users'>; // { method: 'GET'; path: '/users'; body?: never }
type CreateUser = ApiEndpoint<'POST /users'>; // { method: 'POST'; path: '/users'; body: unknown }