difference between var and let in #js

var_let.js

// var is kind of global variable
console.log(a); // undefined
var a = "wow";
console.log(a); // wow
var a = "wowow";
console.log(a); // wowow

// visible globally
// visible only within a block
while (true) {
  var x = 0;
  break;
}
console.log(x); // 0

// Basically let works just like "variable" in other languages (block variable)
console.log(b); // undefined
let b = "woc";
console.log(b); // woc
let b = "wocwoc"; // //SyntaxError

// visible only within a block
while (true) {
  let x = 0;
  break;
}
console.log(x); // "x is not defined"