Lesson 2

Why Variables?

Variables allow us to store data in memory with a name, so we can use it, update it, and work with it throughout our program.

Think of variables as labeled boxes where you can store items. You can change what’s inside the box, and use it whenever you want.

NameStores your name

AgeStores your age

ScoreStores your marks

Without variables, we have to write values again and again. If the value changes, we must change it everywhere!

Bad Example

// Calculate area of a rectangleconsole.log(10 * 5);               // 50console.log(10 * 5 * 2);           // 100console.log(10 * 5 * 2 + 10 * 5);  // 150

let length = 10;let width = 5;console.log(length * width);                        // 50console.log(length * width * 2);                    // 100console.log(length * width * 2 + length * width);   // 150

Easy to read, easy to update, easy to maintain.

Create variables for your name and age, then print them.

JavaScript

1// Write your code here
2
3let name = "Vivek";
4let age = 29;
5
6console.log(name);
7console.log(age);

Variables store data in memory.
They give data a meaningful name.
They help us reuse and update data easily.
They make code readable and maintainable.

Reusability
Use the same data multiple times.
Maintainability
Change once, update everywhere.
Readability
Makes code easy to understand.
Flexibility
Values can be changed anytime.

Always use meaningful names so others (and your future self) can understand your code easily.