title: Html5 canvas and javascript document.getElementById() returns null
body: <p>I'm trying to use html5 canvas and when I do </p>
  
  <pre><code>    var c=document.getElementById('myCanvas');
      var ctx=c.getContext('2d');
      ctx.fillStyle="#FF0000";
      ctx.fillRect(0,0,150,75);
  </code></pre>
  
  <p>and here is the html</p>
  
  <pre><code>    &lt;!DOCTYPE html&gt;
      &lt;html&gt;
      &lt;head&gt;
      &lt;script type="text/javascript" src="game.js"&gt;&lt;/script&gt;
      &lt;/head&gt;
      &lt;body&gt;
      &lt;canvas id="myCanvas" width="512" height="480" style="border:1px solid #000000;"&gt;
      &lt;/canvas&gt;
      &lt;/body&gt;
      &lt;/html&gt;
  </code></pre>
  
  <p>I have no clue what's wrong</p>