#89 Difference between null and undefined in javascript

Difference between null and undefined in JavaScript:

---

🔸 undefined

• A variable that has been declared but not assigned a value is undefined.
• Also, functions return undefined if no return value is specified.
• It is the default value for uninitialized variables.

✅ Example:

let a;
console.log(a); // undefined

function test() {}
console.log(test()); // undefined

---

🔸 null

• null is an intentional absence of any object value.
• It's manually assigned to a variable to indicate “no value”.

✅ Example:

let b = null;
console.log(b); // null

---

✅ Key Differences

• undefined means not assigned yet.
• null means explicitly assigned as empty.
• Type of undefined is "undefined".
• Type of null is "object" (due to a historical bug).