Use Javascript-Object with Json-objects in other methodes

why isn't it working? The ok () method doesn't give me the correct object. But when I use buttons to activate the methods one by one then it works. Even if I write "await" in front of the getdata () method. It doesn't work.

<script> 
   var javaobj = new Object() ;
    
   function ok(){
      console.log(javaobj);
    }

    function getdata()
    {
      var xhttp = new XMLHttpRequest();
      xhttp.onreadystatechange = function () {
        if (xhttp.readyState==4 && xhttp.status==200) {
          javaobj=JSON.parse(xhttp.response);
        }
      }
      xhttp.open("GET", "test.json", true);
      xhttp.send();
    }
  getdata()
  ok()
</script>