1// Primitive types
2const name: string = 'Alice';
3const age: number = 25;
4const isDeveloper: boolean = true;
5
6// Arrays
7const skills: string[] = ['TypeScript', 'React', 'Node.js'];
8
9// Typed objects
10interface Developer {
11  name: string;
12  age: number;
13  skills: string[];
14}
15
16const dev: Developer = {
17  name: 'Alice',
18  age: 25,
19  skills: ['TypeScript', 'React', 'Node.js'],
20};

1// Typed function with parameters and return
2function calculateSalary(hourlyRate: number, hours: number = 35): number {
3  return hourlyRate * hours;
4}
5
6// Arrow function with type
7const sayHello = (name: string): string => `Hello ${name}!`;

1// Union Types
2type ProjectStatus = 'IN_PROGRESS' | 'COMPLETED' | 'ON_HOLD';
3let status: ProjectStatus = 'IN_PROGRESS';
4
5// Generic Types
6interface Response<T> {
7  data: T;
8  status: number;
9}
10
11const apiResponse: Response<Developer> = {
12  data: dev,
13  status: 200,
14};

1interface Project {
2  client?: {
3    name?: string;
4  };
5}
6
7const project: Project = {};
8const clientName = project.client?.name ?? 'Anonymous Client';

1interface Admin {
2  role: 'admin';
3  permissions: string[];
4}
5
6interface User {
7  role: 'user';
8  level: number;
9}
10
11function handleUser(person: Admin | User) {
12  if (person.role === 'admin') {
13    console.log(person.permissions); // TypeScript knows this is an Admin
14  } else {
15    console.log(person.level); // TypeScript knows this is a User
16  }
17}

1// Partial - Makes all properties optional
2type PartialDev = Partial<Developer>;
3
4// Pick - Selects certain properties
5type BasicDev = Pick<Developer, 'name' | 'age'>;
6
7// Omit - Excludes certain properties
8type DevWithoutSkills = Omit<Developer, 'skills'>;