I have ajax function in script as:
 $.ajax({
  url: 'http://www.somesitename.com/admin/exportToCSVAction',
  type: 'GET',
  data:{},
  cache: false,
  success: function() {
  alert("sucess");
  },
  error: function () {
  alert("error");
  }
  });
exportToCSVAction function in php as:
public function exportToCSVAction()
    {
        $exportBatch = 10;
        $order = $this->getTableGateway('order');
        $select = new Select();
        $select->from('order');
        $data = $order->selectWith($select)->toArray();
        $batchDir = __DIR__ . '/../../../../../data/export/batch/' . $exportBatch;
        mkdir($batchDir);
        $fileNameWithFilePath=$batchDir . '/order2.csv';
        if (file_exists($fileNameWithFilePath)) 
        {
            $this->downloadOrderCSVAction($fileNameWithFilePath);
        }
        else
        {
            $csvFile = fopen($batchDir . '/order2.csv', 'w');
            $i = 0;
            foreach($data as $record) {
                if($i==0) fputcsv($csvFile, $this->getCsvHeader($record));
                fputcsv($csvFile, $this->updateCsvLine($record));
                $i++;
            }
            fclose($csvFile);
        }
    }
But every time its returning me error as alert.
When i run it directly through link:
http://www.somesite.com/admin/exportToCSVAction
It returns me result correctly. (downloads the file as expected)
But through ajax it gives me Error as a alert.
Through inspect element network tab i get following:

Please help me.
Where i am making mistake?
Note:
I also tried by removing data from ajax, but no effect
Edit :
$.ajax({
      url: 'http://www.somesitename.com/admin/exportToCSV',
      type: 'GET',
      data:{},
      cache: false,
      success: function() {
      alert("sucess");
      },
      error: function () {
      alert("error");
      }
      });
exportToCSVAction function in php as:
    public function exportToCSVAction()
        {
            $exportBatch = 10;
            $order = $this->getTableGateway('order');
            $select = new Select();
            $select->from('order');
            $data = $order->selectWith($select)->toArray();
            $batchDir = __DIR__ . '/../../../../../data/export/batch/' . $exportBatch;
            mkdir($batchDir);
            $fileNameWithFilePath=$batchDir . '/order2.csv';
            if (file_exists($fileNameWithFilePath)) 
            {
                //Code to download file
            }
            else
            {
                $csvFile = fopen($batchDir . '/order2.csv', 'w');
                $i = 0;
                foreach($data as $record) {
                    if($i==0) fputcsv($csvFile, $this->getCsvHeader($record));
                    fputcsv($csvFile, $this->updateCsvLine($record));
                    $i++;
                }
                fclose($csvFile);
            }
        }
Now with this code i am getting the alet sucess. But not downloading the file