function upload(files){
var uploadBlob = function uploadBlob(files, onload) {
   var xhr = new XMLHttpRequest();
   xhr.open('POST', params.url, true);
   xhr.onload = onload;
   xhr.send(files);
};

var formData = new FormData();
files.map(function (file) {
   formData.append(file.fileName, file);
   return file;
});
uploadBlob(files, function (){ 
   alert("Zakoczono wysyanie.");

   });
   }