title: dynamically double image size
body: <p>I have an embarrassingly simple question: How can I display an image at double its size without hard coding the width and height attributes? Here's what I tried, but I ended up having to just enter 1000 for width and height. Is something wrong with my function? Thanks!</p>
  
  <pre><code>&lt;img onload="double(self.id);" name="bigPic" id="bigPic" src="album1.jpg" height="1000" width="1000"/&gt;
  
      function double(id) {
          var img = document.getElementById(id);
          var dblWdth = img.width * 2;
          var dblHt = img.height * 2;
  
          img.height = dblHt;
          img.width = dblWdth;
      }
  </code></pre>