TypeScript Best Practices for 2024
TypeScript has become an essential tool for JavaScript developers, providing type safety and better developer experience. Here are the best practices you should follow in 2024.
Type Definitions
Use Interfaces for Object Shapes
interface User {
id: number;
name: string;
email: string;
createdAt: Date;
}
interface CreateUserRequest {
name: string;
email: string;
}Prefer Union Types Over Enums
// Instead of enum
type Status = 'pending' | 'approved' | 'rejected';
// Use const assertions for object enums
const StatusMap = {
PENDING: 'pending',
APPROVED: 'approved',
REJECTED: 'rejected'
} as const;
type StatusValue = typeof StatusMap[keyof typeof StatusMap];Function Types
Use Proper Return Types
function processUser(user: User): Promise<ProcessedUser> {
return new Promise((resolve) => {
// Processing logic
resolve({
...user,
processed: true,
processedAt: new Date()
});
});
}Generic Functions
function createApiResponse<T>(
data: T,
success: boolean = true
): ApiResponse<T> {
return {
data,
success,
timestamp: new Date().toISOString()
};
}Configuration
Strict TypeScript Configuration
{
"compilerOptions": {
"strict": true,
"noImplicitAny": true,
"noImplicitReturns": true,
"noUnusedLocals": true,
"noUnusedParameters": true
}
}Common Patterns
Type Guards
function isString(value: unknown): value is string {
return typeof value === 'string';
}
function processValue(value: string | number) {
if (isString(value)) {
// TypeScript knows value is string here
return value.toUpperCase();
}
// TypeScript knows value is number here
return value * 2;
}Utility Types
// Pick specific properties
type UserSummary = Pick<User, 'id' | 'name'>;
// Make all properties optional
type PartialUser = Partial<User>;
// Make all properties required
type RequiredUser = Required<User>;Best Practices Summary
- Always use strict mode in TypeScript configuration
- Prefer interfaces over type aliases for object shapes
- Use union types instead of enums when possible
- Implement proper error handling with typed errors
- Leverage utility types for code reuse
- Use type guards for runtime type checking
Conclusion
Following these TypeScript best practices will help you write more maintainable and type-safe code. The key is to leverage TypeScript's type system to catch errors at compile time rather than runtime.