You Don’t Know JavaScript, Scope and Closures Chapter 5 Question, this code gives me an error

JavaScript
1

This code is from YDKJS book part 2 Scope and Clousers, when I run it it gives me an typeError that fn is not a function at bar(); why so?

function foo() {
  var a = 2;
  function baz() {
    console.log(a);
  }
  fn = baz;
}

function bar(fn) {
  fn();
}

foo();
bar();
2

fn is the function parameter

you are trying to call undefined, undefined is not a function

3

I have added
var fn;
at the beginning of the code and still get the same result

4

It’s a question of scope, fn is the name of the parameter of bar

so when bar is called fn takes the value of whatever is passed as argument,

no argument means that fn is undefined.

This fn has no relation with the fn in the global scope