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   formData.append('file', $("#ufile")[0].files[0]);
      
      console.log(formData);
      
      BX.ajax.runComponentAction("rinlet:test_form", "loadFile", {
         mode: "class",
         data: formData,
         type:     "POST", //метод отправки
         cache: false,
         contentType: false,
         processData: false,
         dataType: "json" //формат данных
         }).then(function (data) {
         // обработка ответа
      file_fid = data.fid;
      });   

<?

public function loadFileAction($file) {
               //загрузка файла   
         $input_name = 'file';         
         $file = $_FILES[$input_name];
         $arr_file = CFile::MakeFileArray($file['tmp_name']);
         $fid = CFile::SaveFile($arr_file, "riher");
      
         $data = array(
         'fid' =>  $fid, 
         'file' =>  $file, 
         //'iblock_id' => $arComponentParameters,
         'error'   => $error,
         'success' => $success
         );
   
         header('Content-Type: application/json');
         echo json_encode($data, JSON_UNESCAPED_UNICODE);
         }
?>