Understanding Objects

Objects are a common way to store data, but unlike arrays, they don’t use numbered indexes — they use keys and values.

{ name: "Sallu bhai" }

Here, name is the key, and "Sallu bhai" is the value.

Creating an Object

const student = {
  name: "Sallu",
  status: "unmarried",
  favAnimal: "blackbuck",
  courses: ["driving", "acting"]
};

Accessing Object Properties

To access an object’s data, we use dot notation (.).

console.log(student.status);    // "unmarried"
console.log(student.courses[0]); // "driving"

Adding and Modifying Properties

Objects are mutable — you can add new keys or change existing ones.

const car = { brand: "Mahindra", model: "XUV" };

// Modify an existing property
car.model = "Thar";

// Add a new property
car.year = 2022;

console.log(car); // { brand: "Mahindra", model: "Thar", year: 2022 }

Nested Objects

Objects can contain other objects. This is useful when you want to group related information together.

const student = {
  name: "Alex",
  age: 20,
  address: {
    city: "Noida",
    pincode: 201301
  }
};

console.log(student.name);            // "Alex"
console.log(student.address.city);    // "Noida"
console.log(student.address.pincode); // 201301

Methods in Objects

Objects can also hold functions. When a function belongs to an object, we call it a method.

const user = {
  username: "coder123",
  greet: function () {
    console.log(`Hello, welcome back ${this.username}!`);
  }
};

user.greet(); // "Hello, welcome back coder123!"

Try it yourself

1. Profile Builder: Create an object named smartphone with keys for brand, model, storage, and price. Print a sentence using these values (e.g., “I have a 128GB iPhone.”).
2. Property Mutation: Update smartphone’s price to a lower value, and add a new boolean property called is5G.
3. Object Method: Create an object named calculator with properties num1 and num2, and a method called add that returns their sum using this.