Null and Undefined

👨‍💼 JavaScript has two special values that represent "nothing" or "no value":

undefined - A variable that hasn't been assigned a value yet
null - An intentional "empty" or "nothing" value

These might seem similar, but they have different meanings:

undefined means "this doesn't have a value yet"
null means "this intentionally has no value"

🐨 Open

index.js

and explore these special values:

Create a variable notAssigned without giving it a value
Create a variable intentionallyEmpty and set it to null
Log both variables with their types using typeof
Compare them with == and === to see the difference

💰 You can declare a variable without a value:

let myVariable
console.log(myVariable) // undefined

🦉 Fun fact: typeof null returns "object" - this is actually a bug in JavaScript from the very first version, but it can't be fixed now because too much code depends on it!

📜 null on MDN 📜 undefined on MDN

01. Hello JavaScript/04. Null and Undefined (💪 problem)

Null and Undefined