Uncaught SyntaxError: Unexpected end of JSON input
at JSON.parse (<anonymous>)
at XMLHttpRequest.xmlhttp.onreadystatechange

unction chatTest() {
      var xmlhttp = getXmlHttp();
      xmlhttp.open("POST","functionsTest.php",true);
      xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
      xmlhttp.send("update=1");
      xmlhttp.onreadystatechange = function(){
      if (xmlhttp.readyState == 4) {
      if (xmlhttp.status == 200) {
      var response = xmlhttp.responseText;
      response = JSON.parse(response);
      if (array.length == response.length) return;
      var start = array.length;
      array = response;
      var message = document.getElementById("chat").innerHTML;
      for (i = start; i < array.length; i++) {
      message = message + "<p><b>" + array[i].name + ":</b> " + array[i].message + "</p>"
     }
     document.getElementById("chat").innerHTML = message;
     document.getElementById("chat").scrollTop = 1000000;
      }
      }
      }
      setTimeout("chatTest()", 1000);
      }

elseif(isset($_POST["update"])) {
      $string = file_get_contents("messageTest.txt");
     $array = explode("n", $string);
     $result = array();
     for ($i = 0; $i < count($array); $i++) {
         $temp = explode(";", $array[$i]);
         $result[$i]["name"] = $temp[0];
         $result[$i]["message"] = $temp[1];

     }
     echo json_encode($result);     }