Missing time to update the chat

I found a chat system on the internet and I'm trying to unravel the code of it, I would like to know how to take the time of the next update of the message box. Here is a snippet of code:

   //initiates the first data query
function receiveChatText() {
    if (httpReceiveChat.readyState == 4 || httpReceiveChat.readyState == 0) {
    httpReceiveChat.open("GET",GetChaturl + '&lastID=' + lastID, true);
      httpReceiveChat.onreadystatechange = handlehHttpReceiveChat; 
    httpReceiveChat.send(null);
    }
}


//deals with the servers' reply to requesting new content
function handlehHttpReceiveChat() {

  if (httpReceiveChat.readyState == 4) {

     var results = document.getElementById("outputList");
     results.innerHTML = httpReceiveChat.responseText;

     setTimeout('receiveChatText();',60000); //executes the next data query in 4 seconds

  }
}

In case I would like to take the time that is missing from this setTimeout if possible, I have already researched and failed.