CODE EXAMPLE FOR JAVASCRIPT

upload excel file using jquery ajax

$('#input-file').change(function() {

      var url = '/back-end-url';
      var form_data = new FormData();
      var xhr = new XMLHttpRequest();

      $.each(this.files, function (key, value) {
          form_data.append('file', value)
      })

      xhr.open('POST', url, true)
      xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest")
      xhr.send(form_data)

      xhr.onreadystatechange(function() {
          if(xhr.readyState == XMLHttpRequest.DONE) {
               var res = JSON.parse(xhr.responseText)
          }
      })

})