Question

I’m doing a ajax function for wp. But i get always the response 0. I see the code of the file admin-ajax.php and see this:

if ( empty( $_REQUEST['action'] ) )
    die( '0' );

This is my js function ajax.

function fnc(){

            var ajax=new  XMLHttpRequest();
            ajax.open("POST", "<?php echo get_site_url(); ?>/wp-admin/admin-ajax.php");



                ajax.onreadystatechange= function(){
                    if (ajax.readyState === 4) {
                        if (ajax.status === 200) {
                            alert(ajax.responseType);
                            alert(ajax.responseText);
                        } else {
                            alert('There was a problem with the request.');
                        }
                    }
                }
                ajax.send("action=some_function");


        }

Answer 1

In order to have the send string be used as form data, you will probably need to add the following header:

ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

Without this, PHP will not turn the raw POST data into $_POST/$_REQUEST variables.