PTF Training session. Frontend for Backend Developers.

var vs let.md

function varTest() {
 var x = 31;
 if (true) {
   var x = 71;      // same variable!
   console.log(x);  // 71
 }   
 console.log(x);    // 71
}

function letTest() {
 let x = 31;
 if (true) {
   let x = 71;      // different variable
   console.log(x);  // 71
 }
 console.log(x);    // 31
}

var a = 0;
var b = 0;

if (a === 0) {
 let a = 1; // The scope is inside the if-block
 var b = 1; // The scope is inside the function

 console.log(a);  // 1
 console.log(b);  // 1
}

console.log(a); // 0
console.log(b); // 1