Using let and const in JavaScript

In modern JavaScript (ES6+), let and const are preferred over var for declaring variables. They offer block scoping and help avoid bugs related to variable hoisting and redeclaration.

🔁 let – Mutable Variable

Use let when the value of a variable might change later.

let count = 0;
count = count + 1; // ✅ valid
console.log(count); // 1

Scope: Block-scoped (within { ... })

🔒 const – Constant (Read-only)

Use const when the value should not be reassigned.

const pi = 3.14;
pi = 3.1415; // ❌ Error: Assignment to constant variable

Note: Objects and arrays declared with const can still be mutated:

const user = { name: "John" };
user.name = "Jane"; // ✅ Allowed

const arr = [1, 2, 3];
arr.push(4); // ✅ Allowed

📌 Key Differences

🎯 When to Use?

• Use const by default for safety.
• Use let if you know the variable will change.