title: Uncaught TypeError: Cannot read property 'play,src, or click' of null
body: <p>Ok so Chrome is give me this error <strong>Uncaught TypeError: Cannot read property 'play' of null</strong> this keep on popping up if switch it to click or focus function. So in my simple HTML code I have </p>
  
  <pre><code>        &lt;audio id="f1Menu" controls&gt;
              &lt;source src="../sounds/menu/menu_f1_help.mp3" type="audio/mp3"&gt;
              &lt;source src="../sounds/menu/menu_f1_help.ogg" type="audio/ogg"&gt;
          &lt;/audio&gt;
          &lt;audio id="f2Menu" controls&gt;
              &lt;source src="../sounds/menu/menu_f2_email.mp3" type="audio/mp3"&gt;
              &lt;source src="../sounds/menu/menu_f2_email.ogg" type="audio/ogg"&gt;
          &lt;/audio&gt;
          &lt;audio id="f3Menu" controls&gt;
              &lt;source src="../sounds/menu/menu_f3_password.mp3" type="audio/mp3"&gt;
              &lt;source src="../sounds/menu/menu_f3_password.ogg" type="audio/ogg"&gt;
          &lt;/audio&gt;
          &lt;audio id="f4Menu" controls&gt;
              &lt;source src="../sounds/menu/menu_f4_enter.mp3" type="audio/mp3"&gt;
              &lt;source src="../sounds/menu/menu_f4_enter.ogg" type="audio/ogg"&gt;
          &lt;/audio&gt;
  </code></pre>
  
  <p>and the the Javascript script which is load on the same page</p>
  
  <p>//this javascript which is attach to html page.</p>
  
  <pre><code>     AudioMode().playAudio("f1",2000);
  
  function AudioMode()
  {
      this.playAudio = function(key,delay)
      {
              alert(key + "Menu"); //this display on screen with the the id combo im looking for
  
              //however the document.getElementById is not find it???
              document.getElementById(key + "Menu").play(); 
  
      }
  }
  </code></pre>
  
  <p>If need more info please let me know. I place min code which giving me error the function work just not in it.</p>