I used FormData to get and send form to backend.

I want to send multiple file without using multiple property of input tag (because of work purpose)

Here is my code

area += '<div id="select-file-'+ newFileIndex +  index + '">' +
    '<input type="file" name="part_kpi[' + index + '][mid_year_review_employee_file][]" id="file_' + nameInput + newFileIndex + i + '" placeholder="" onchange="showFile(this,' +  index + ',' +  newFileIndex + ',\'' +  nameInput + '\')">' +
    '<label for="file_' + nameInput + newFileIndex + i + '" class="custom-file-upload">Choose Files</label>' +
    '</div>'
$('#attachment-area' + index).html(area);

That mean whenever I upload a file, I will regenerate Choose Files button

But if I use $('#attachment-area' + index).html(area); the Form Data did not send my file to BE (if I comment out this line it sent normally)

What I should do?