title: Can Javascript check a file for content changes?
body: <p>Example:</p>
  
  <p>I have </p>
  
  <pre><code>var r = new FileReader();
      r.onload = function(e) {
          drawGraph(r.result);
      }
      r.readAsText(f);
  </code></pre>
  
  <p>drawing a graph from the file f input by the user.</p>
  
  <p>Is there a way to check to see if the file f has been changed and then re load it's content without needing for the user to pick the file again?</p>