Q5- What is the difference between null and undefined?

The main difference between null and undefined in JavaScript is their meaning and how they’re assigned.

• undefined means a variable has been declared but not assigned any value.
• null means a variable has been intentionally assigned an empty or “no value” state.

🧾 Example:

let a;
console.log(a);  // undefined (no value assigned)

let b = null;
console.log(b);  // null (explicitly assigned no value)

✅ In short:

• undefined → the variable exists but has no value yet.
• null → the variable was given an empty value on purpose.