In JavaScript, objects are used to store related information together.

They help us represent real-world entities like:

• a person

• a student

• a car

• a product

Instead of storing data in many separate variables, we can group it inside one object.

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1. What Are Objects?

An object is a collection of key-value pairs.

Example:

let person = {
  name: "Pankaj",
  age: 25,
  city: "Patna"
};

Here:

Key	Value
name	"Pankaj"
age	25
city	"Patna"

So an object stores information about something in a structured way.

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Real-World Example

Imagine storing information about a person.

Instead of doing this:

let name = "Pankaj";
let age = 25;
let city = "Patna";

We can group everything inside an object.

let person = {
  name: "Pankaj",
  age: 25,
  city: "Patna"
};

This makes the data organized and easier to manage.

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Object Structure Visualization

person
   ↓
+----------------+
| name : Pankaj  |
| age  : 25      |
| city : Patna   |
+----------------+

Each property has:

key : value

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2. Creating Objects

Objects are created using curly braces {}.

Example:

let car = {
  brand: "BMW",
  color: "Black",
  speed: 200
};

Now we have an object called car with three properties.

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3. Accessing Object Properties

We can access properties in two ways:

• Dot notation

• Bracket notation

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Dot Notation

This is the most common method.

Example:

let person = {
  name: "Pankaj",
  age: 25
};

console.log(person.name);

Output

Pankaj

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Bracket Notation

We can also access properties using brackets.

Example:

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

Output

25

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Difference Between Dot and Bracket

Method	Example
Dot notation	person.name
Bracket notation	person["name"]

Bracket notation is useful when the property name is dynamic.

Example:

let key = "name";

console.log(person[key]);

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4. Updating Object Properties

We can change property values easily.

Example:

let person = {
  name: "Pankaj",
  age: 25
};

person.age = 26;

console.log(person);

Output

{ name: "Pankaj", age: 26 }

Here we updated age from 25 → 26.

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5. Adding New Properties

We can add properties anytime.

Example:

let person = {
  name: "Pankaj"
};

person.city = "Patna";

console.log(person);

Output

{ name: "Pankaj", city: "Patna" }

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6. Deleting Properties

We can remove properties using delete.

Example:

let person = {
  name: "Pankaj",
  age: 25
};

delete person.age;

console.log(person);

Output

{ name: "Pankaj" }

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7. Looping Through Object Keys

To access all properties, we can use a for...in loop.

Example:

let person = {
  name: "Pankaj",
  age: 25,
  city: "Patna"
};

for (let key in person) {
  console.log(key, person[key]);
}

Output

name Pankaj
age 25
city Patna

Explanation:

key → property name
person[key] → value

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Array vs Object

Sometimes beginners get confused between arrays and objects.

Feature	Array	Object
Structure	Ordered list	Key-value pairs
Access	Index	Key
Example	[10,20,30]	{name:"Pankaj"}

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Example

Array:

let fruits = ["Apple", "Banana", "Mango"];

console.log(fruits[0]);

Object:

let person = {
  name: "Pankaj"
};

console.log(person.name);

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Visual Comparison

Array

[ Apple , Banana , Mango ]
   0        1        2

Object

{
 name : "Pankaj"
 age  : 25
 city : "Patna"
}

Arrays use index numbers, objects use keys.

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Practical Example

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

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

Output

Rahul
Computer Science

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Assignment

Open your console:

Right Click → Inspect → Console

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1️⃣ Create a Student Object

let student = {
  name: "Amit",
  age: 20,
  course: "BCA"
};

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2️⃣ Update One Property

student.age = 21;

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3️⃣ Add a New Property

student.city = "Delhi";

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4️⃣ Print All Keys and Values

for (let key in student) {
  console.log(key, student[key]);
}

Expected output example

name Amit
age 21
course BCA
city Delhi

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Final Tip

Objects are one of the most important data structures in JavaScript.

They are used everywhere, including:

• user profiles

• API responses

• configurations

• databases

• real-world application data

Mastering objects will make JavaScript much more powerful and practical for you.