Variables

Scope

---

function myFunction() {
  var pizzaName = 'Margarita';
  // Code here can use pizzaName
}
 
// Code here can't use pizzaName

Block Scoped Variables

---

if (true) {
  const statusMessage = 'Logged in.';
}
// Uncaught ReferenceError...
console.log(statusMessage);

Global Variables

---

// Variable declared globally
const color = 'blue';
 
function printColor() {
  console.log(color);
}
 
printColor(); // => blue

let vs var

---

var is scoped to the nearest function block, and let is scoped to the nearest enclosing block.

let

for (let i = 0; i < 3; i++) {
  // This is the Max Scope for 'let'
  // i accessible ✔️
}
// i not accessible ❌

var

for (var i = 0; i < 3; i++) {
  var y = i// i accessible ✔️
}
// i accessible ✔️
console.log(i, y)

Gesamtübersicht

---

const globalConst = "globalConst"
var globalVar = "globalVar"
let globalLet = "globalLet"
console.log(globalConst, globalVar, globalLet)
//✔️, ✔️, ✔️
 
if(true){
	console.log(globalConst, globalVar, globalLet)
	//✔️, ✔️, ✔️
	const ifConst = "ifConst"
	var ifVar = "ifVar"
	let ifLet = "ifLet"
	console.log(ifConst, ifVar, ifLet)
	//✔️, ✔️, ✔️
}
console.log(ifConst, ifVar, ifLet)
//❌, ✔️, ❌