Logically let should have block scope, how this snippet is returning number?

function fn() {
  let ax = bx = 110;
  ax++;
  return ax;
}
fn()
console.log(typeof bx)
console.log(typeof ax)

its answer is // undefined number .
I am very confused, how it is possible. as ax , bx is in scope

>Solution :

When we write let ax = bx = 110;, we are not doing

let ax = 110;
let bx = 110;

In fact there is no keyword in front of bx, and hence it is considered to be from the outer scope. In this case, bx becomes a part of global scope. And hence it is available outside.

PS:

One hacky way to do it in one line:

function fn() {
  let [ax,bx] = [110,110];
  ax++;
  return ax;
}
fn()
console.log(typeof bx)
console.log(typeof ax)