BLOB Save

cloud.functions.performSave = function (blob, filename, successCallback, errorCallback) {
    window.requestFileSystem(
                  LocalFileSystem.PERSISTENT, 0,
                  function onFileSystemSuccess(fileSystem) {
                      fileSystem.root.getFile(filename, { create: true }, function (fileEntry) {
                          fileEntry.createWriter(function (fileWriter) {
                              fileWriter.onwriteend = function (e) {
                                  successCallback();
                              };
                              fileWriter.onerror = function (e) {
                                  errorCallback(e);
                              };
                              fileWriter.write(blob);
                          }, errorCallback);
                      }, errorCallback);
                  })
}