title: What's the difference between BlobBuilder and the new Blob constructor?
body: <p>The W3 announced that they intend to deprecate the <a href="https://developer.mozilla.org/en/DOM/BlobBuilder">BlobBuilder API</a> in preference for the new <a href="http://dev.w3.org/2006/webapi/FileAPI/#dfn-Blob">Blob API.</a></p>
  
  <p>If I am already using BlobBuilder in a JavaScript app, how can I convert to using this new Blob API? The old WebKitBlobBuilder is still available in the latest WebKit (and Chrome Canary), but it will soon be removed. Before you could write something like this:</p>
  
  <pre><code>var bb = new BlobBuilder();
  bb.append(arrayBuffer);
  var blob = bb.getBlob(mimeString);
  </code></pre>
  
  <p>How could this be rewritten to use the new Blob constructor? Thank you.</p>