Nefunkční výpis v js

<script src="chat.js"></script>
<?php 
echo'<div id="chat""></div>';
?>

function chat()
{
     var soubor = "extract.php";


        if (window.ActiveXObject)
        {
          httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
        }
        else
        {
          httpRequest = new XMLHttpRequest();
        }
        httpRequest.open("GET", soubor, true);
        httpRequest.onreadystatechange= function () {processRequest(); } ;
        httpRequest.send(null);
      }
}

function processRequest()
{
  if (httpRequest.readyState == 4)
  {
    if(httpRequest.status == 200)
    {
      var chat = document.getElementById("chat");
      chat.innerHTML = httpRequest.responseText;
    }
    else
    {
        alert("Chyba pri nacitani chatu
"+ httpRequest.status +":"+ httpRequest.statusText);
    }
	setTimeout('chat();', 5000);
  }
}