Objects

1// Object type annotation inline
2let user: { name: string; age: number } = {
3  name: "Alice",
4  age: 30,
5};
6 
7// Using an interface
8interface Person {
9  name: string;
10  age: number;
11  email?: string; // Optional property
12}
13 
14const alice: Person = {
15  name: "Alice",
16  age: 30,
17  email: "alice@example.com",
18};
19 
20const bob: Person = {
21  name: "Bob",
22  age: 25,
23  // email is optional, so we can omit it
24};
25 
26// Readonly properties
27interface Config {
28  readonly apiKey: string;
29  readonly endpoint: string;
30}
31 
32const config: Config = {
33  apiKey: "secret-key-123",
34  endpoint: "https://api.example.com",
35};
36 
37// config.apiKey = "new-key"; // Error: Cannot assign to 'apiKey'
38 
39// Nested objects
40interface Company {
41  name: string;
42  address: {
43    street: string;
44    city: string;
45    country: string;
46  };
47}
48 
49const company: Company = {
50  name: "Tech Corp",
51  address: {
52    street: "123 Main St",
53    city: "San Francisco",
54    country: "USA",
55  },
56};
57 
58console.log(`${alice.name} is ${alice.age} years old`);
59console.log(`Company: ${company.name}, ${company.address.city}`);