// TypeScript test file
import { EventEmitter } from 'events';
import type { Request, Response } from 'express';
// Interface
interface User {
id: number;
name: string;
email: string;
}
// Type alias
type UserRole = 'admin' | 'user' | 'guest';
// Enum
enum Status {
Active = 'ACTIVE',
Inactive = 'INACTIVE',
Pending = 'PENDING'
}
// Abstract class
abstract class BaseService {
protected apiUrl: string;
constructor(apiUrl: string) {
this.apiUrl = apiUrl;
}
abstract fetchData<T>(): Promise<T>;
}
// Generic class
class UserService extends BaseService {
private users: Map<number, User>;
constructor(apiUrl: string) {
super(apiUrl);
this.users = new Map();
}
async fetchData<User>(): Promise<User> {
// Implementation
return {} as User;
}
addUser(user: User): void {
this.users.set(user.id, user);
}
getUser(id: number): User | undefined {
return this.users.get(id);
}
}
// Function with type annotations
function processUsers(users: User[], role: UserRole): User[] {
return users.filter(user => {
// Some filtering logic
return true;
});
}
// Namespace
namespace Utils {
export function formatDate(date: Date): string {
return date.toISOString();
}
export class Logger {
log(message: string): void {
console.log(message);
}
}
}
// Type guard
function isUser(obj: any): obj is User {
return obj && typeof obj.id === 'number' && typeof obj.name === 'string';
}
export { UserService, processUsers, Status, Utils };
export type { User, UserRole };
