When a user clicks on a button (in a form), a javascript prompt box will appear asking for the user's name, then I want to send that javascript promp data into php, so that I can send it to a phpmyadmin database. Note that I have tried using an xmlhttprequest, but that didnt work, because the website is in https and not http
Here is the html form:
<form method="post" id="user_form" action="Pages/Intro/Intro.php">
   <input class="button" id ="start_button" type="button"  name ="txt" onclick="loadUserName()" value="Go to Game(push Twice)">
    <br>
    <input class="button" id="help_button" name="help" type="button" onclick="location.href='Pages/Help/Help.html';" value="Help/F.A.Q" >
    <br>
  </form>
But, I am not sure how to send this form data
JS (not sending to https):
function sendTextToServer(txt) {
                  var xhr = new XMLHttpRequest();
                  var formData = new FormData(myForm);
                  xhr.open("POST", "https://foo.php"); //Server goes after Post Method
                  //formData.append("txt", txt);
                  xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
                  xhr.addEventListener("readystatechange", function() {
                    if (xhr.readyState == 4 && xhr.status == 200) {      // state DONE, status OK
                       // your request has been received, do what you want with the result here.
                    }
                  });
                  xhr.send(formData);
                }
 
    