Ajax Question

AJAX : What is the equivalent function of beforeSend function in XMLHttpRequest

In $.ajax there is beforeSend function, but now I'm trying to use XMLHttpRequest, I'm looking for equivalent function of beforeSend in $.ajax. How can i implement it in here.

Here is my xhr code,

xhr = new XMLHttpRequest();
var url = '../ajax/ajax_edit/update_ajax_staffUser.php';

if(file.files.length !== 0){

if(!check(fileUpload.type)){
alert("This file format not accepted");
return false;
}
xhr.open('post', url+param, true);
xhr.setRequestHeader('Content-Type','multipart/form-data');
xhr.setRequestHeader('X-File-Name', fileUpload.name);
xhr.setRequestHeader('X-File-Size', fileUpload.size);
xhr.setRequestHeader('X-File-Type', fileUpload.type);
xhr.send(fileUpload);
}else{
xhr.open('post', url+param, true);
xhr.setRequestHeader('Content-Type','multipart/form-data');
xhr.send(fileUpload);
}


xhr.onreadystatechange = function(e){
if(xhr.readyState===4){
if(xhr.status==200){
$('.bounce_dim').show();
setTimeout(function(){
$('.trigger_danger_alert_changable_success').show().delay(5000).fadeOut();
$('#palitan_ng_text_success').html('User successfully modified');
$('#frm_edit_staffUser')[0].reset();
$('#modal_staff').modal('hide');
$('.bounce_dim').hide();
},1000);
getUserStaffTable();
}
}
}


Since the users are uploading image to my web, I need to make a waiting interface before fires the call since the image size are too large.

Answer

You can do this by just putting the beforeSend() function before your XHR intantiation, like this:

beforeSend();
xhr = new XMLHttpRequest();

But you should define your beforeSend() function before the code above:

var beforeSend = function(){
    // your code here
}