Chapter 14: Real-World Projects

Authored by syscook.dev

What are Real-World TypeScript Projects?

Real-world TypeScript projects are practical applications that demonstrate the use of TypeScript in production environments. These projects showcase best practices, architectural patterns, and real-world challenges that developers face when building scalable, maintainable applications.

Key Project Types:

Full-Stack Applications: Frontend and backend with TypeScript
API Services: RESTful and GraphQL APIs
Desktop Applications: Electron and native apps
Mobile Applications: React Native and cross-platform
Libraries and Packages: Reusable TypeScript libraries
Microservices: Distributed systems with TypeScript

Why Build Real-World Projects?

1. Practical Experience

Real-world projects provide hands-on experience with TypeScript in production scenarios.

// Real-world example: E-commerce API
interface Product {
  id: string;
  name: string;
  price: number;
  category: string;
  inventory: number;
  createdAt: Date;
  updatedAt: Date;
}

interface CreateProductRequest {
  name: string;
  price: number;
  category: string;
  inventory: number;
}

interface UpdateProductRequest extends Partial<CreateProductRequest> {
  id: string;
}

class ProductService {
  constructor(
    private productRepository: ProductRepository,
    private eventBus: EventBus
  ) {}

  async createProduct(request: CreateProductRequest): Promise<Product> {
    // Validation
    if (request.price <= 0) {
      throw new ValidationError('Price must be positive');
    }

    if (request.inventory < 0) {
      throw new ValidationError('Inventory cannot be negative');
    }

    // Create product
    const product = await this.productRepository.create({
      ...request,
      id: generateId(),
      createdAt: new Date(),
      updatedAt: new Date()
    });

    // Emit event
    await this.eventBus.emit('product.created', product);

    return product;
  }

  async updateProduct(request: UpdateProductRequest): Promise<Product> {
    const existingProduct = await this.productRepository.findById(request.id);
    if (!existingProduct) {
      throw new NotFoundError('Product not found');
    }

    const updatedProduct = await this.productRepository.update(request.id, {
      ...request,
      updatedAt: new Date()
    });

    await this.eventBus.emit('product.updated', updatedProduct);

    return updatedProduct;
  }
}

2. Architecture Patterns

Real-world projects demonstrate proper architectural patterns and design principles.

// Clean Architecture example
// Domain Layer
interface User {
  id: string;
  email: string;
  name: string;
  createdAt: Date;
}

interface UserRepository {
  findById(id: string): Promise<User | null>;
  findByEmail(email: string): Promise<User | null>;
  save(user: User): Promise<User>;
}

// Application Layer
interface CreateUserCommand {
  email: string;
  name: string;
}

interface CreateUserResult {
  success: boolean;
  user?: User;
  error?: string;
}

class CreateUserUseCase {
  constructor(
    private userRepository: UserRepository,
    private emailService: EmailService
  ) {}

  async execute(command: CreateUserCommand): Promise<CreateUserResult> {
    try {
      // Check if user already exists
      const existingUser = await this.userRepository.findByEmail(command.email);
      if (existingUser) {
        return {
          success: false,
          error: 'User with this email already exists'
        };
      }

      // Create user
      const user: User = {
        id: generateId(),
        email: command.email,
        name: command.name,
        createdAt: new Date()
      };

      const savedUser = await this.userRepository.save(user);

      // Send welcome email
      await this.emailService.sendWelcomeEmail(savedUser.email);

      return {
        success: true,
        user: savedUser
      };
    } catch (error) {
      return {
        success: false,
        error: 'Failed to create user'
      };
    }
  }
}

// Infrastructure Layer
class DatabaseUserRepository implements UserRepository {
  constructor(private db: Database) {}

  async findById(id: string): Promise<User | null> {
    const result = await this.db.query('SELECT * FROM users WHERE id = ?', [id]);
    return result.rows[0] || null;
  }

  async findByEmail(email: string): Promise<User | null> {
    const result = await this.db.query('SELECT * FROM users WHERE email = ?', [email]);
    return result.rows[0] || null;
  }

  async save(user: User): Promise<User> {
    await this.db.query(
      'INSERT INTO users (id, email, name, created_at) VALUES (?, ?, ?, ?)',
      [user.id, user.email, user.name, user.createdAt]
    );
    return user;
  }
}

How to Build Real-World Projects?

1. Project 1: Task Management API

Project Structure

task-management-api/
├── src/
│   ├── domain/
│   │   ├── entities/
│   │   │   ├── Task.ts
│   │   │   └── User.ts
│   │   ├── repositories/
│   │   │   ├── TaskRepository.ts
│   │   │   └── UserRepository.ts
│   │   └── services/
│   │       ├── TaskService.ts
│   │       └── UserService.ts
│   ├── infrastructure/
│   │   ├── database/
│   │   │   ├── Database.ts
│   │   │   └── migrations/
│   │   ├── repositories/
│   │   │   ├── DatabaseTaskRepository.ts
│   │   │   └── DatabaseUserRepository.ts
│   │   └── external/
│   │       └── EmailService.ts
│   ├── application/
│   │   ├── use-cases/
│   │   │   ├── CreateTaskUseCase.ts
│   │   │   ├── UpdateTaskUseCase.ts
│   │   │   └── DeleteTaskUseCase.ts
│   │   └── dto/
│   │       ├── CreateTaskDTO.ts
│   │       └── UpdateTaskDTO.ts
│   ├── presentation/
│   │   ├── controllers/
│   │   │   └── TaskController.ts
│   │   ├── middleware/
│   │   │   ├── AuthMiddleware.ts
│   │   │   └── ValidationMiddleware.ts
│   │   └── routes/
│   │       └── taskRoutes.ts
│   └── main.ts
├── tests/
│   ├── unit/
│   ├── integration/
│   └── e2e/
├── package.json
├── tsconfig.json
└── README.md

Core Implementation

// src/domain/entities/Task.ts
export interface Task {
  id: string;
  title: string;
  description?: string;
  status: TaskStatus;
  priority: TaskPriority;
  dueDate?: Date;
  userId: string;
  createdAt: Date;
  updatedAt: Date;
}

export enum TaskStatus {
  TODO = 'todo',
  IN_PROGRESS = 'in_progress',
  DONE = 'done',
  CANCELLED = 'cancelled'
}

export enum TaskPriority {
  LOW = 'low',
  MEDIUM = 'medium',
  HIGH = 'high',
  URGENT = 'urgent'
}

// src/domain/repositories/TaskRepository.ts
export interface TaskRepository {
  findById(id: string): Promise<Task | null>;
  findByUserId(userId: string): Promise<Task[]>;
  save(task: Task): Promise<Task>;
  update(id: string, updates: Partial<Task>): Promise<Task>;
  delete(id: string): Promise<void>;
}

// src/application/use-cases/CreateTaskUseCase.ts
export interface CreateTaskCommand {
  title: string;
  description?: string;
  priority: TaskPriority;
  dueDate?: Date;
  userId: string;
}

export class CreateTaskUseCase {
  constructor(
    private taskRepository: TaskRepository,
    private userRepository: UserRepository
  ) {}

  async execute(command: CreateTaskCommand): Promise<Task> {
    // Validate user exists
    const user = await this.userRepository.findById(command.userId);
    if (!user) {
      throw new Error('User not found');
    }

    // Create task
    const task: Task = {
      id: generateId(),
      title: command.title,
      description: command.description,
      status: TaskStatus.TODO,
      priority: command.priority,
      dueDate: command.dueDate,
      userId: command.userId,
      createdAt: new Date(),
      updatedAt: new Date()
    };

    return await this.taskRepository.save(task);
  }
}

// src/presentation/controllers/TaskController.ts
export class TaskController {
  constructor(
    private createTaskUseCase: CreateTaskUseCase,
    private updateTaskUseCase: UpdateTaskUseCase,
    private deleteTaskUseCase: DeleteTaskUseCase
  ) {}

  async createTask(req: Request, res: Response): Promise<void> {
    try {
      const command: CreateTaskCommand = {
        title: req.body.title,
        description: req.body.description,
        priority: req.body.priority,
        dueDate: req.body.dueDate ? new Date(req.body.dueDate) : undefined,
        userId: req.user.id
      };

      const task = await this.createTaskUseCase.execute(command);
      res.status(201).json(task);
    } catch (error) {
      res.status(400).json({ error: error.message });
    }
  }

  async getTasks(req: Request, res: Response): Promise<void> {
    try {
      const tasks = await this.taskRepository.findByUserId(req.user.id);
      res.json(tasks);
    } catch (error) {
      res.status(500).json({ error: 'Internal server error' });
    }
  }
}

2. Project 2: React Dashboard with TypeScript

Project Structure

react-dashboard/
├── src/
│   ├── components/
│   │   ├── common/
│   │   │   ├── Button/
│   │   │   │   ├── Button.tsx
│   │   │   │   ├── Button.module.css
│   │   │   │   └── index.ts
│   │   │   ├── Modal/
│   │   │   └── Table/
│   │   ├── layout/
│   │   │   ├── Header/
│   │   │   ├── Sidebar/
│   │   │   └── Layout.tsx
│   │   └── features/
│   │       ├── auth/
│   │       │   ├── LoginForm/
│   │       │   └── AuthProvider/
│   │       ├── dashboard/
│   │       │   ├── StatsCard/
│   │       │   ├── Chart/
│   │       │   └── Dashboard.tsx
│   │       └── users/
│   │           ├── UserList/
│   │           ├── UserForm/
│   │           └── UserDetails/
│   ├── hooks/
│   │   ├── useAuth.ts
│   │   ├── useApi.ts
│   │   └── useLocalStorage.ts
│   ├── services/
│   │   ├── api.ts
│   │   ├── authService.ts
│   │   └── userService.ts
│   ├── types/
│   │   ├── auth.ts
│   │   ├── user.ts
│   │   └── api.ts
│   ├── utils/
│   │   ├── constants.ts
│   │   ├── helpers.ts
│   │   └── validation.ts
│   ├── App.tsx
│   └── main.tsx
├── public/
├── package.json
├── tsconfig.json
├── vite.config.ts
└── tailwind.config.js

Core Implementation

// src/types/user.ts
export interface User {
  id: string;
  email: string;
  name: string;
  role: UserRole;
  avatar?: string;
  createdAt: string;
  updatedAt: string;
}

export enum UserRole {
  ADMIN = 'admin',
  USER = 'user',
  MODERATOR = 'moderator'
}

export interface CreateUserRequest {
  email: string;
  name: string;
  role: UserRole;
  password: string;
}

export interface UpdateUserRequest {
  id: string;
  email?: string;
  name?: string;
  role?: UserRole;
}

// src/services/userService.ts
export class UserService {
  constructor(private apiClient: ApiClient) {}

  async getUsers(): Promise<User[]> {
    const response = await this.apiClient.get<User[]>('/users');
    return response.data;
  }

  async getUserById(id: string): Promise<User> {
    const response = await this.apiClient.get<User>(`/users/${id}`);
    return response.data;
  }

  async createUser(userData: CreateUserRequest): Promise<User> {
    const response = await this.apiClient.post<User>('/users', userData);
    return response.data;
  }

  async updateUser(userData: UpdateUserRequest): Promise<User> {
    const { id, ...updateData } = userData;
    const response = await this.apiClient.put<User>(`/users/${id}`, updateData);
    return response.data;
  }

  async deleteUser(id: string): Promise<void> {
    await this.apiClient.delete(`/users/${id}`);
  }
}

// src/hooks/useUsers.ts
export function useUsers() {
  const [users, setUsers] = useState<User[]>([]);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  const fetchUsers = useCallback(async () => {
    setLoading(true);
    setError(null);
    
    try {
      const userService = new UserService(apiClient);
      const usersData = await userService.getUsers();
      setUsers(usersData);
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Failed to fetch users');
    } finally {
      setLoading(false);
    }
  }, []);

  const createUser = useCallback(async (userData: CreateUserRequest) => {
    try {
      const userService = new UserService(apiClient);
      const newUser = await userService.createUser(userData);
      setUsers(prev => [...prev, newUser]);
      return newUser;
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Failed to create user');
      throw err;
    }
  }, []);

  const updateUser = useCallback(async (userData: UpdateUserRequest) => {
    try {
      const userService = new UserService(apiClient);
      const updatedUser = await userService.updateUser(userData);
      setUsers(prev => prev.map(user => 
        user.id === updatedUser.id ? updatedUser : user
      ));
      return updatedUser;
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Failed to update user');
      throw err;
    }
  }, []);

  const deleteUser = useCallback(async (id: string) => {
    try {
      const userService = new UserService(apiClient);
      await userService.deleteUser(id);
      setUsers(prev => prev.filter(user => user.id !== id));
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Failed to delete user');
      throw err;
    }
  }, []);

  useEffect(() => {
    fetchUsers();
  }, [fetchUsers]);

  return {
    users,
    loading,
    error,
    fetchUsers,
    createUser,
    updateUser,
    deleteUser
  };
}

// src/components/features/users/UserList.tsx
interface UserListProps {
  onUserSelect: (user: User) => void;
  onUserEdit: (user: User) => void;
  onUserDelete: (user: User) => void;
}

export function UserList({ onUserSelect, onUserEdit, onUserDelete }: UserListProps) {
  const { users, loading, error, deleteUser } = useUsers();
  const [selectedUser, setSelectedUser] = useState<User | null>(null);

  const handleUserSelect = (user: User) => {
    setSelectedUser(user);
    onUserSelect(user);
  };

  const handleUserEdit = (user: User) => {
    onUserEdit(user);
  };

  const handleUserDelete = async (user: User) => {
    if (window.confirm(`Are you sure you want to delete ${user.name}?`)) {
      try {
        await deleteUser(user.id);
        onUserDelete(user);
      } catch (error) {
        console.error('Failed to delete user:', error);
      }
    }
  };

  if (loading) {
    return <div className="flex justify-center p-8">Loading...</div>;
  }

  if (error) {
    return <div className="text-red-500 p-4">Error: {error}</div>;
  }

  return (
    <div className="bg-white shadow rounded-lg">
      <div className="px-4 py-5 sm:p-6">
        <h3 className="text-lg leading-6 font-medium text-gray-900 mb-4">
          Users
        </h3>
        <div className="overflow-x-auto">
          <table className="min-w-full divide-y divide-gray-200">
            <thead className="bg-gray-50">
              <tr>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Name
                </th>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Email
                </th>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Role
                </th>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Actions
                </th>
              </tr>
            </thead>
            <tbody className="bg-white divide-y divide-gray-200">
              {users.map((user) => (
                <tr
                  key={user.id}
                  className={`hover:bg-gray-50 cursor-pointer ${
                    selectedUser?.id === user.id ? 'bg-blue-50' : ''
                  }`}
                  onClick={() => handleUserSelect(user)}
                >
                  <td className="px-6 py-4 whitespace-nowrap">
                    <div className="flex items-center">
                      <div className="flex-shrink-0 h-10 w-10">
                        <img
                          className="h-10 w-10 rounded-full"
                          src={user.avatar || '/default-avatar.png'}
                          alt={user.name}
                        />
                      </div>
                      <div className="ml-4">
                        <div className="text-sm font-medium text-gray-900">
                          {user.name}
                        </div>
                      </div>
                    </div>
                  </td>
                  <td className="px-6 py-4 whitespace-nowrap text-sm text-gray-500">
                    {user.email}
                  </td>
                  <td className="px-6 py-4 whitespace-nowrap">
                    <span className={`inline-flex px-2 py-1 text-xs font-semibold rounded-full ${
                      user.role === UserRole.ADMIN
                        ? 'bg-red-100 text-red-800'
                        : user.role === UserRole.MODERATOR
                        ? 'bg-yellow-100 text-yellow-800'
                        : 'bg-green-100 text-green-800'
                    }`}>
                      {user.role}
                    </span>
                  </td>
                  <td className="px-6 py-4 whitespace-nowrap text-sm font-medium">
                    <button
                      onClick={(e) => {
                        e.stopPropagation();
                        handleUserEdit(user);
                      }}
                      className="text-indigo-600 hover:text-indigo-900 mr-3"
                    >
                      Edit
                    </button>
                    <button
                      onClick={(e) => {
                        e.stopPropagation();
                        handleUserDelete(user);
                      }}
                      className="text-red-600 hover:text-red-900"
                    >
                      Delete
                    </button>
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        </div>
      </div>
    </div>
  );
}

3. Project 3: TypeScript Library

Project Structure

typescript-library/
├── src/
│   ├── index.ts
│   ├── utils/
│   │   ├── validation.ts
│   │   ├── formatting.ts
│   │   └── helpers.ts
│   ├── types/
│   │   ├── common.ts
│   │   └── api.ts
│   └── classes/
│       ├── ApiClient.ts
│       └── Cache.ts
├── tests/
│   ├── utils/
│   ├── classes/
│   └── integration/
├── examples/
│   ├── basic-usage.ts
│   └── advanced-usage.ts
├── docs/
│   ├── README.md
│   └── API.md
├── package.json
├── tsconfig.json
├── rollup.config.js
└── .npmignore

Core Implementation

// src/index.ts
export * from './utils/validation';
export * from './utils/formatting';
export * from './utils/helpers';
export * from './types/common';
export * from './types/api';
export * from './classes/ApiClient';
export * from './classes/Cache';

// src/utils/validation.ts
export interface ValidationRule<T> {
  validate(value: T): boolean;
  message: string;
}

export class Validator<T> {
  private rules: ValidationRule<T>[] = [];

  addRule(rule: ValidationRule<T>): this {
    this.rules.push(rule);
    return this;
  }

  validate(value: T): { isValid: boolean; errors: string[] } {
    const errors: string[] = [];
    
    for (const rule of this.rules) {
      if (!rule.validate(value)) {
        errors.push(rule.message);
      }
    }

    return {
      isValid: errors.length === 0,
      errors
    };
  }
}

export const commonRules = {
  required: <T>(message: string = 'This field is required'): ValidationRule<T> => ({
    validate: (value: T) => value != null && value !== '',
    message
  }),
  
  minLength: (min: number, message?: string): ValidationRule<string> => ({
    validate: (value: string) => value.length >= min,
    message: message || `Must be at least ${min} characters long`
  }),
  
  maxLength: (max: number, message?: string): ValidationRule<string> => ({
    validate: (value: string) => value.length <= max,
    message: message || `Must be no more than ${max} characters long`
  }),
  
  email: (message: string = 'Must be a valid email address'): ValidationRule<string> => ({
    validate: (value: string) => /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(value),
    message
  }),
  
  min: (min: number, message?: string): ValidationRule<number> => ({
    validate: (value: number) => value >= min,
    message: message || `Must be at least ${min}`
  }),
  
  max: (max: number, message?: string): ValidationRule<number> => ({
    validate: (value: number) => value <= max,
    message: message || `Must be no more than ${max}`
  })
};

// src/classes/ApiClient.ts
export interface ApiClientConfig {
  baseURL: string;
  timeout?: number;
  headers?: Record<string, string>;
}

export interface ApiResponse<T> {
  data: T;
  status: number;
  statusText: string;
  headers: Record<string, string>;
}

export class ApiClient {
  private config: ApiClientConfig;

  constructor(config: ApiClientConfig) {
    this.config = {
      timeout: 5000,
      headers: {
        'Content-Type': 'application/json',
        ...config.headers
      },
      ...config
    };
  }

  async get<T>(url: string, params?: Record<string, any>): Promise<ApiResponse<T>> {
    const queryString = params ? this.buildQueryString(params) : '';
    const fullUrl = `${this.config.baseURL}${url}${queryString}`;
    
    const response = await fetch(fullUrl, {
      method: 'GET',
      headers: this.config.headers,
      signal: AbortSignal.timeout(this.config.timeout!)
    });

    return this.handleResponse<T>(response);
  }

  async post<T>(url: string, data?: any): Promise<ApiResponse<T>> {
    const response = await fetch(`${this.config.baseURL}${url}`, {
      method: 'POST',
      headers: this.config.headers,
      body: data ? JSON.stringify(data) : undefined,
      signal: AbortSignal.timeout(this.config.timeout!)
    });

    return this.handleResponse<T>(response);
  }

  async put<T>(url: string, data?: any): Promise<ApiResponse<T>> {
    const response = await fetch(`${this.config.baseURL}${url}`, {
      method: 'PUT',
      headers: this.config.headers,
      body: data ? JSON.stringify(data) : undefined,
      signal: AbortSignal.timeout(this.config.timeout!)
    });

    return this.handleResponse<T>(response);
  }

  async delete<T>(url: string): Promise<ApiResponse<T>> {
    const response = await fetch(`${this.config.baseURL}${url}`, {
      method: 'DELETE',
      headers: this.config.headers,
      signal: AbortSignal.timeout(this.config.timeout!)
    });

    return this.handleResponse<T>(response);
  }

  private buildQueryString(params: Record<string, any>): string {
    const searchParams = new URLSearchParams();
    
    Object.entries(params).forEach(([key, value]) => {
      if (value != null) {
        searchParams.append(key, String(value));
      }
    });

    const queryString = searchParams.toString();
    return queryString ? `?${queryString}` : '';
  }

  private async handleResponse<T>(response: Response): Promise<ApiResponse<T>> {
    if (!response.ok) {
      throw new Error(`HTTP error! status: ${response.status}`);
    }

    const data = await response.json();
    const headers: Record<string, string> = {};
    
    response.headers.forEach((value, key) => {
      headers[key] = value;
    });

    return {
      data,
      status: response.status,
      statusText: response.statusText,
      headers
    };
  }
}

// examples/basic-usage.ts
import { Validator, commonRules, ApiClient } from '../src';

// Validation example
const userValidator = new Validator<string>()
  .addRule(commonRules.required('Name is required'))
  .addRule(commonRules.minLength(2, 'Name must be at least 2 characters'))
  .addRule(commonRules.maxLength(50, 'Name must be no more than 50 characters'));

const emailValidator = new Validator<string>()
  .addRule(commonRules.required('Email is required'))
  .addRule(commonRules.email('Must be a valid email address'));

// API client example
const apiClient = new ApiClient({
  baseURL: 'https://api.example.com',
  timeout: 10000
});

async function fetchUser(id: string) {
  try {
    const response = await apiClient.get<{ id: string; name: string; email: string }>(`/users/${id}`);
    return response.data;
  } catch (error) {
    console.error('Failed to fetch user:', error);
    throw error;
  }
}

// Usage
const nameValidation = userValidator.validate('John Doe');
console.log('Name validation:', nameValidation);

const emailValidation = emailValidator.validate('[email protected]');
console.log('Email validation:', emailValidation);

fetchUser('123').then(user => {
  console.log('User:', user);
});

Best Practices for Real-World Projects

1. Project Structure

// Good: Clear separation of concerns
src/
├── domain/          // Business logic
├── infrastructure/  // External dependencies
├── application/     // Use cases
└── presentation/    // Controllers, UI

2. Error Handling

// Good: Comprehensive error handling
try {
  const result = await riskyOperation();
  return { success: true, data: result };
} catch (error) {
  if (error instanceof ValidationError) {
    return { success: false, error: error.message, field: error.field };
  }
  if (error instanceof NetworkError) {
    return { success: false, error: 'Network error', retryable: true };
  }
  return { success: false, error: 'Unknown error' };
}

3. Testing

// Good: Comprehensive testing
describe('UserService', () => {
  let userService: UserService;
  let mockRepository: jest.Mocked<UserRepository>;

  beforeEach(() => {
    mockRepository = createMockRepository();
    userService = new UserService(mockRepository);
  });

  describe('createUser', () => {
    it('should create user with valid data', async () => {
      // Test implementation
    });

    it('should throw error for invalid data', async () => {
      // Test implementation
    });
  });
});

4. Documentation

// Good: Comprehensive documentation
/**
 * Creates a new user in the system
 * @param userData - The user data to create
 * @returns Promise that resolves to the created user
 * @throws {ValidationError} When user data is invalid
 * @throws {DuplicateEmailError} When email already exists
 * @example
 * ```typescript
 * const user = await userService.createUser({
 *   email: '[email protected]',
 *   name: 'John Doe'
 * });
 * ```
 */
async createUser(userData: CreateUserRequest): Promise<User> {
  // Implementation
}

Common Pitfalls and Solutions

1. Poor Project Structure

// ❌ Problem: Everything in one file
// app.ts - 1000+ lines of code

// ✅ Solution: Proper separation
// src/domain/entities/User.ts
// src/domain/repositories/UserRepository.ts
// src/application/use-cases/CreateUserUseCase.ts
// src/presentation/controllers/UserController.ts

2. Inadequate Error Handling

// ❌ Problem: Generic error handling
try {
  await riskyOperation();
} catch (error) {
  console.error(error);
}

// ✅ Solution: Specific error handling
try {
  await riskyOperation();
} catch (error) {
  if (error instanceof ValidationError) {
    handleValidationError(error);
  } else if (error instanceof NetworkError) {
    handleNetworkError(error);
  } else {
    handleUnknownError(error);
  }
}

3. Missing Tests

// ❌ Problem: No tests
// Production code without tests

// ✅ Solution: Comprehensive testing
describe('UserService', () => {
  // Unit tests
});

describe('UserController', () => {
  // Integration tests
});

describe('User API', () => {
  // E2E tests
});

Conclusion

Real-world TypeScript projects demonstrate the practical application of TypeScript in production environments. By understanding:

What real-world projects involve and their types
Why they're important for practical experience and learning
How to structure and implement various project types

You can build scalable, maintainable applications that solve real problems. These projects showcase best practices, architectural patterns, and real-world challenges that developers face when building production-ready applications.

Next Steps

Start building your own real-world projects
Contribute to open-source TypeScript projects
Learn about deployment and DevOps practices
Move on to Chapter 15: Best Practices & Patterns

This tutorial is part of the TypeScript Mastery series by syscook.dev

What are Real-World TypeScript Projects?​

Key Project Types:​

Why Build Real-World Projects?​

1. Practical Experience​

2. Architecture Patterns​

How to Build Real-World Projects?​

1. Project 1: Task Management API​

Project Structure​

Core Implementation​

2. Project 2: React Dashboard with TypeScript​

Project Structure​

Core Implementation​

3. Project 3: TypeScript Library​

Project Structure​

Core Implementation​

Best Practices for Real-World Projects​

1. Project Structure​

2. Error Handling​

3. Testing​

4. Documentation​

Common Pitfalls and Solutions​

1. Poor Project Structure​

2. Inadequate Error Handling​

3. Missing Tests​

Conclusion​

Next Steps​

What are Real-World TypeScript Projects?

Key Project Types:

Why Build Real-World Projects?

1. Practical Experience

2. Architecture Patterns

How to Build Real-World Projects?

1. Project 1: Task Management API

Project Structure

Core Implementation

2. Project 2: React Dashboard with TypeScript

Project Structure

Core Implementation

3. Project 3: TypeScript Library

Project Structure

Core Implementation

Best Practices for Real-World Projects

1. Project Structure

2. Error Handling

3. Testing

4. Documentation

Common Pitfalls and Solutions

1. Poor Project Structure

2. Inadequate Error Handling

3. Missing Tests

Conclusion

Next Steps