var http = false;
var userName;
if(navigator.appName == "Microsoft Internet Explorer") {
  http = new ActiveXObject("Microsoft.XMLHTTP");
} else {
   http = new XMLHttpRequest();
}

function denunciar(userName) {
  http.open("GET", "/get_denunciar/"+ userName, true);
  http.onreadystatechange=function() {
    if(http.readyState == 4) {
      document.getElementById('denunciar').innerHTML = http.responseText;
    }
  }
  http.send(null);
}