title: How to save a image to HTML5 filesystem with the url of image
body: <p>I am trying to use HTML5 system to store images of my website, and I find there are many example to show how to store a local image to your chrome file system but I can't find the way to get a image by web url and then store it in HTML5 file system.</p>
  
  <p>This is my code, but it's wrong.</p>
  
  <pre><code>        lib.ajax.get(file , function(xhr, data){
              if(xhr.status == 200){
                  fs.root.getFile("test.jpg", {create: true}, function(fileEntry) {
                      // Create a FileWriter object for our FileEntry (log.txt).
                      fileEntry.createWriter(function(fileWriter) {
                          fileWriter.onwriteend = function(e) {
                              console.log('Write completed.');
                          };
  
                          fileWriter.onerror = function(e) {
                              console.log('Write failed: ' + e.toString());
                          };
                          // Create a new Blob and write it to log.txt.
                          var bb = new BlobBuilder(); // Note: window.WebKitBlobBuilder in Chrome 12.
                          bb.append(data);
                          fileWriter.write(bb.getBlob('image/jpeg'));
                          callback &amp;&amp; callback("test.jpg");
                      }, errorHandler);
  
                  }, errorHandler);
              }
          });
  </code></pre>