debug4.html

<script>

var myVariable = 10;

function bar(myVariable) {
  function foo(myVariable) {
    myVariable = 11;
  }
  foo();
  console.log(myVariable);
}

bar(myVariable); // 10
console.log(myVariable); // 10

</script>

global context:
  myVariable = 10
  bar context:
    myVariable = 10
    foo context:
      myVariable = 11

10
10