title: JS: how to add methods to an instance of an object?
body: <p>here is my html</p>
  
  <pre><code>    &lt;script src="game.js"&gt;&lt;/script&gt;
      &lt;script src="help.js"&gt;&lt;/script&gt;
  $(document).ready(function () {
      game = new Game();
      game.start();
  })
  &lt;/script&gt;
  </code></pre>
  
  <p>game.js:</p>
  
  <pre><code>var Game = function() {
      this.start = function() {
          console.log('start');       
      };
  
  };
  </code></pre>
  
  <p>help.js</p>
  
  <pre><code>Game.help = function() {
      alert('help');
  }
  </code></pre>
  
  <p>however game.help() raises an error</p>
  
  <p>What is wrong ? and how to fix it ?</p>
  
  <p>Error: help is undefined</p>