QBW file via ajax

I try to upload a huge qbw file in chunks using this function.
But the file type is empty and when
I try to open it with a dedicated program , it tells me that the file has an unexpected format.
Also after merging the chunks, they are merged into one huge file,
but the file has 0 kb size.
I tried many contentType,
headers and reader methods to read chunks but the same result.
Can anyone knows what is wrong ?

// slice files in chunk chunky

      chunky : function(file, loadedSize) 
{ let chunkSize = 1048576 ; //1024*1024; size of one chunk var totalFileSize = file.size; // total size of file 
var noOfChunks = Math.ceil(totalFileSize/chunkSize); 
let reader = new FileReader();
let blob = file.slice(loadedSize, chunkSize); //a single chunk in starting of step size let requestNumber = 1;
 reader.readAsBinaryString(blob); // reader.readAsDataURL( blob ); console.log('totalSize'+totalFileSize); 
console.log('noOfChunksTosend' + requestNumber);
 reader.onloadend = function (event)
 {
 if (event.target.readyState === FileReader.DONE) { //read request completed // no more chunks to send 
if(event.target.result) 
{ console.log('loadedSize' + loadedSize); console.log('rezult::' + event.target.result);
 var dataToBeSent = { 
bloby: event.target.result, 
 fileName: file.name, 
fileType: file.type, // empty ?? fileSize: totalFileSize, 
loadedSize: loadedSize,
 requestNumber: requestNumber
 } 
jQuery.ajax({ 
url: IntegrationServer.path + '/uploadfileInChuncks', 
type: "POST",
 method: 'POST', 
data: dataToBeSent, 
// contenttype: "multipart/form-data", 
processData: false, 
contentType: false,
 // this dataType: 'json',
 cache:false, }).done(function (response)
 { console.log('received response: ' + response);