What Are Objects in JavaScript?

Objects are used to store related information in the form of key-value pairs.

For example, a student has a name, age, and course. Instead of storing these details in separate variables, we can group them into one object.

let student = { name: "John", age: 22, course: "Computer Science" };

Here, name, age, and course are keys, while "John", 22, and "Computer Science" are their values.

1. Accessing Object Properties

We can access object properties in two common ways.

Dot notation:

console.log(student.name);

Output: John

Bracket notation:

console.log(student["age"]);

Output: 22

Both methods help us access the values stored inside an object.

2. Adding Properties

We can add new properties to an object whenever needed.

student.city = "Chennai"; console.log(student);

This adds a new property called city with the value "Chennai".

3. Updating Properties

We can change the value of an existing property.

student.age = 23; console.log(student.age);

Output: 23

Here, the student's age changes from 22 to 23.

4. Deleting Properties

We can use the delete operator to remove a property from an object.

delete student.course; console.log(student);

This removes the course property from the object.

5. Objects with Functions

An object can also contain functions as properties. These functions are commonly called methods.

let person = { name: "John", greet: function() { console.log("Hello!"); } }; person.greet();

Output: Hello!

Here, greet() is a method of the person object.

6. Looping Through Objects

We can use a for...in loop to access an object's property names and values.

let product = { name: "Laptop", price: 50000, brand: "HP" }; for (let key in product) { console.log(key, product[key]); }

This prints each property name along with its value.

Why Are Objects Important?

Objects help us:

  • Store related information together.
  • Organize data clearly.
  • Add, update, and delete properties.
  • Represent real-world things such as students, products, and employees.
  • Create useful applications such as product management systems and shopping carts.