JavaScript Variables – Introduction

📘 What is a Variable?

A variable is a container used to store data values. In JavaScript, variables allow you to store, update, and use data throughout your program.

🎯 Why Do We Use Variables?

  • Store data (numbers, text, objects)
  • Reuse values easily
  • Make code readable and maintainable

🧱 Declaring Variables in JavaScript

JavaScript provides three ways to declare variables:

  • var – Old way (function scoped)
  • let – Modern way (block scoped)
  • const – Constant value (cannot be reassigned)

💻 Variable Examples

var name = "Ahmed";
let age = 25;
const country = "Egypt";

age = 26; // allowed
// country = "USA"; ❌ not allowed
⚠️ Note: Always prefer let and const instead of var.

📏 Variable Naming Rules

  • Must start with a letter, $ or _
  • Cannot start with a number
  • No spaces allowed
  • Case-sensitive (age ≠ Age)

🧪 Try It Yourself

Click the button to create variables and display them: