Post Data with the JavaScript XMLHttpRequest javascript challenge

JavaScript
1

Tell us what’s happening:
My tests pass, but I can’t get the result specified in the challenge when I click the button

Your code so far


<script>
  document.addEventListener('DOMContentLoaded',function(){
    document.getElementById('sendMessage').onclick=function(){
    
      var userName=document.getElementById('name').value;
      // Add your code below this line
      req=new XMLHttpRequest();
req.open("POST",url,true);
req.setRequestHeader('Content-Type','text/plain');
req.onreadystatechange=function(){
  if(req.readyState==4 && req.status==200){
    document.getElementsByClassName('message')[0].innerHTML=req.responseText  + 'loves cats';
  }
};
req.send(userName);
      
      // Add your code above this line
    };
  });
</script>
<style>
  body {
    text-align: center;
    font-family: "Helvetica", sans-serif;
  }
  h1 {
    font-size: 2em;
    font-weight: bold;
  }
  .box {
    border-radius: 5px;
    background-color: #eee;
    padding: 20px 5px;
  }
  button {
    color: white;
    background-color: #4791d0;
    border-radius: 5px;
    border: 1px solid #4791d0;
    padding: 5px 10px 8px 10px;
  }
  button:hover {
    background-color: #0F5897;
    border: 1px solid #0F5897;
  }
</style>
<h1>Cat Friends</h1> 
<p class="message box">
  Reply from Server will be here
</p>
<p>
  <label for="name">Your name:
    <input type="text" id="name"/>
  </label>
  <button id="sendMessage">
    Send Message
  </button>
</p>

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.102 Safari/537.36.

Link to the challenge:

2

Same here. I think the problem is that the variable ‘url’ doesn’t have a value. That means the line
req.open(“POST”,url,true);
is not talking to any web adress that might answer us. It seems this challenge isn’t fully implemented, only checks the syntax.