title: How to add a new property to an existing prototype/construction function along with its parameter
body: <p>this is for educational purposes only, say I have an existing prototype/ constructor function:</p>
  
  <pre><code>var Dog = function(name, age, color){
  this.name = name;
  this.age = age;
  this.color = color;
  };
  
  var pitBull = new Dog('Rocky', 5, 'black');
  </code></pre>
  
  <p>that I want to add  (via coding) a new parameter called <code>type</code> to it like this:</p>
  
  <pre><code>    var Dog = function(name, age, color, type){
      // code goes here.. };
  </code></pre>
  
  <p>and at the same time I want to add a new property with the exact name like so:</p>
  
  <pre><code>    this.type = type;
  </code></pre>
  
  <p>so I can do this:</p>
  
  <pre><code>    var pitBull = new Dog('Rocky', 5, 'black', 'PitBull');
  </code></pre>
  
  <p>any ideas?</p>