Understanding Objects in JavaScript

When working with JavaScript, we often need to store multiple related pieces of information together. For example, details about a person such as their name, age, and city.

Instead of storing these values separately, JavaScript provides objects to group related data together.

What Are Objects and Why Are They Needed?

An object is a collection of key-value pairs used to store related data.

Think of an object like a profile card.

Example: A person profile

• Name → Ram

• Age → 22

• City → Pune

In JavaScript, this can be stored as an object.

let person = {
  name: "Ram",
  age: 22,
  city: "Pune"
};

console.log(person);

Here:

• name, age, and city are keys

• "Ram", 22, "Pune" are values

Creating Objects

Objects are created using curly braces {}.

Example:

let student = {
  name: "Suraj",
  age: 21,
  course: "Computer Science"
};

console.log(student);

This object stores information about a student.

Accessing Object Properties

There are two ways to access object properties.

1. Dot Notation

The most common method.

console.log(student.name);
console.log(student.age);

Output

Suraj
21

2. Bracket Notation

Bracket notation is useful when the key is stored in a variable.

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

Output

Computer Science

Both methods access the same data.

Updating Object Properties

Object values can be updated easily.

Example:

student.age = 22;

console.log(student.age);

Output

22

Here we changed the age from 21 to 22.

Adding New Properties

We can also add new properties to an object.

Example:

student.city = "Pune";

console.log(student);

Now the object contains:

name
age
course
city

Deleting Properties

To remove a property, use the delete keyword.

Example:

delete student.city;

console.log(student);

Now the city property is removed.

Looping Through Object Keys

Sometimes we want to print all keys and values of an object.

We can use a for...in loop.

Example:

let student = {
  name: "Suraj",
  age: 21,
  course: "Computer Science"
};

for (let key in student) {
  console.log(key + ": " + student[key]);
}

Output

name: Suraj
age: 21
course: Computer Science

This loop goes through every property in the object.

Difference Between Array and Object

Array	Object
Stores ordered data	Stores key-value pairs
Accessed by index	Accessed by key
Example: [10, 20, 30]	Example: {name:"Ram"}

Example array:

let numbers = [10, 20, 30];
console.log(numbers[0]);

Example object:

let person = {
  name: "Ram",
  age: 22
};

console.log(person.name);

Arrays are good for lists, while objects are good for structured data.

Example

Create an object representing a student.

let student = {
  name: "Suraj",
  age: 21,
  course: "Web Development"
};

Update one property:

student.age = 22;

Print all keys and values:

for (let key in student) {
  console.log(key + ": " + student[key]);
}

Conclusion

Objects are one of the most important features in JavaScript. They allow developers to store related information in a structured way using key-value pairs.

Key things to remember:

• Objects store data as key-value pairs

• Use dot notation or bracket notation to access properties

• Properties can be updated, added, or deleted

• for...in loops help iterate through object keys

Understanding objects will help you build more organized and scalable JavaScript applications.