Sample xhr request

xhr.js

var formData = new FormData();
var str_url = '/ajax';
formData.append('id', int_id);
var xhr = new XMLHttpRequest();
xhr.open('POST', str_url, true);
xhr.onload = function(e) {
   if (this.status == 200) {
      if (/success/i.test(this.responseText)) {
         alert('Category Box deleted successfully.');
      } else {
         alert(this.responseText);
      }
   }
};
xhr.send(formData);