Scope vs. Visibility in Javascript

scope-visibility.js

/**
 * The scope of the first "one" variable is the region of the function a, included function b.
 * Its visibility though doesn't coincide, because the second variable called "one" within the function "b"
 * hides it. This doesn't mean that the scope is reduced.
 */
function a() {
  const one = 1;

  function b() {
    const one = -1;
    const two = 2;

    console.log(one);
    console.log(two);
  }

  b();
}

a();