title: javascript readAsArrayBuffer returns empty Array Buffer
body: <p>I am trying to read a local file using the FileReader readAsArrayBuffer property.
  The read is success and in the "onload" callback, I see the Array Buffer object in reader.result. But the Array Buffer is just empty. The length is set, but not the data. How do I get this data?</p>
  
  <p>Here is my code</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  
  &lt;body&gt;
      &lt;input type="file" id="file" /&gt;
  &lt;/body&gt;
  
  &lt;script&gt;
      function handleFileSelect(evt) {
  
          var files = evt.target.files; // FileList object
  
          var selFile = files[0];
          var reader = new FileReader();
          reader.onload = function(e) {
              console.log(e.target.result);
          };
  
          reader.onerror = function(e) {
              console.log(e);
          };
          reader.readAsArrayBuffer(selFile);
      }
  
  
      document.getElementById('file').addEventListener('change', handleFileSelect, false);
  &lt;/script&gt;
  
  &lt;/html&gt;
  </code></pre>
  
  <p>the console output for reader.result</p>
  
  <pre><code>e.target.result
  ArrayBuffer {}
  e.target.result.byteLength
  25312
  </code></pre>
  
  <p>Can anyone tell me how to get this data?
  is there some security issue? 
  There is no error, the onerror is not executed.</p>
  
  <p><em>From comments:</em> Can you please let me know how to access the buffer contents? I am actually trying to play an audio file using <code>AudioContext</code>... For that I would need the buffer data...</p>