Javascript - modified scoping example from p. 36 of Javascript: The Good Parts

gistfile1.js

var foo = function() {
 var a = 3, b = 5;
  
  console.log("a: " +  a + ", b: " + b);
  if (typeof c === "undefined") { console.log("c is undefined"); } 
  console.log("---");
  
  var bar = function() {
    var b = 7, c = 11;
    
    console.log("a: " +  a + ", b: " + b + ", c:" + c);
    console.log("---");    
    
    a += b + c;
    
    console.log("a: " +  a + ", b: " + b + ", c:" + c);    
    console.log("---");    
  };
  bar();
  
  console.log("a: " +  a + ", b: " + b);
  if (typeof c === "undefined") { console.log("c is undefined"); } 

};

foo();