在使用 AJAX 时，我得到 - 404 (Not Fount)

Question

当我尝试通过 AJAX 将值发送到特定页面时，出现错误 - 404（未找到）

这是显示的错误信息 :------------------------------------:

获取 http://localhost/titodiary/chat_message_send_data.php?user_logged_in_id=1&chat_with_friend_id=2&chat_message_input_text=ghost 404（未找到）

:------------------------------------:

以下是我使用的代码-

:------------------------------------:

    var user_logged_in_id = document.getElementById("user_logged_in_id").value;
    var chat_with_friend_id = document.getElementById("chat_with_friend_id").value;
    var chat_message_input_text = document.getElementById("chat_message_input_text").value.trim();
    var chat_message_send_button = document.getElementById("chat_message_send_button");
    var this_is_a_test_text = document.getElementById("this_is_a_test_text");


    chat_message_send_button.onclick = ()=>{
        // let's start Ajax
        let xhr = new XMLHttpRequest(); // creating XML object
        xhr.open("POST", "chat_message_send_data.php?user_logged_in_id=" + user_logged_in_id + "&chat_with_friend_id=" + chat_with_friend_id + "&chat_message_input_text=" + chat_message_input_text, true);
        xhr.onload = ()=>{
            if(xhr.readyState === XMLHttpRequest.DONE){
                if (xhr.status === 200){
                    let data = xhr.response;
                    this_is_a_test_text.innerHTML = data;
                }
            }
        }
        xhr.send();
    }

:------------------------------------:

谁能找出问题所在？