utility_types

interface User {
  id: number;
  name: string;
  email: string;
}

function updateUser(userId: number, updates: Partial<User>) {
  // Imagine this function updates a user in the database
  console.log(userId, updates);
}

updateUser(1, { name: 'Alice' }); // Works perfectly, 'email' is optional


interface Config {
  host?: string;
  port?: number;
}

function initializeServer(config: Required<Config>) {
  console.log(`Starting server at ${config.host}:${config.port}`);
}

initializeServer({ host: 'localhost', port: 8080 }); // Works fine
initializeServer({ host: 'localhost' }); // Error: Property 'port' is missing


interface Point {
  x: number;
  y: number;
}

const point: Readonly<Point> = { x: 1, y: 2 };

point.x = 5; // Error: Cannot assign to 'x' because it is a read-only property


type Status = 'pending' | 'completed' | 'failed';

const statusMessages: Record<Status, string> = {
  pending: 'The task is pending',
  completed: 'The task has been completed',
  failed: 'The task has failed',
};

console.log(statusMessages.pending); // 'The task is pending'


interface User {
  id: number;
  name: string;
  email: string;
}

type UserSummary = Pick<User, 'id' | 'name'>;

const userSummary: UserSummary = {
  id: 1,
  name: 'Alice',
};

console.log(userSummary);


interface User {
  id: number;
  name: string;
  email: string;
}

type UserWithoutEmail = Omit<User, 'email'>;

const user: UserWithoutEmail = {
  id: 1,
  name: 'Bob',
};

console.log(user);


type Status = 'pending' | 'completed' | 'failed';
type NonFailedStatus = Exclude<Status, 'failed'>;

const status: NonFailedStatus = 'completed'; // Works
const anotherStatus: NonFailedStatus = 'failed'; // Error