// 
// Set Chat Message 
// 
 
function set_chat_msg() 
{ 
  if(typeof XMLHttpRequest != "undefined") 
  { 
    oxmlHttpSend = new XMLHttpRequest(); 
  } 
  else if (window.ActiveXObject) 
  { 
    oxmlHttpSend = new ActiveXObject("Microsoft.XMLHttp"); 
  } 
  if(oxmlHttpSend == null) 
  { 
    alert("Browser does not support XML Http Request"); 
    return; 
  } 
 
  var url = "chat_send_ajax.php"; 
  var strname="noname"; 
  var strmsg=""; 
  if (document.getElementById("txtname") != null) 
  { 
    strname = document.getElementById("txtname").value; 
    document.getElementById("txtname").readOnly=true; 
  } 
  if (document.getElementById("txtmsg") != null) 
  { 
    strmsg = document.getElementById("txtmsg").value; 
    document.getElementById("txtmsg").value = ""; 
  } 
 
  url += "" + strname + "&msg=" + strmsg; 
  oxmlHttpSend.open("GET",url,true); 
  oxmlHttpSend.send(null); 
} 

require_once('dbconnect.php'); 
 
db_connect(); 
 
$msg = $_GET["msg"]; 
$dt = date("Y-m-d H:i:s"); 
$user = $_GET["name"]; 
 
$sql="INSERT INTO chat(USERNAME,CHATDATE,MSG) " . 
   "values(" . quote($user) . "," . 
   quote($dt) . "," . quote($msg) . ");"; 
 
   echo $sql; 
 
$result = mysql_query($sql); 
if(!$result) 
{ 
  throw new Exception('Query failed: ' . mysql_error()); 
  exit(); 
} 

var t = setInterval(function(){get_chat_msg()},5000);

// 
// General Ajax Call 
// 
 
var oxmlHttp; 
var oxmlHttpSend; 
 
function get_chat_msg() 
{ 
  if(typeof XMLHttpRequest != "undefined") 
  { 
    oxmlHttp = new XMLHttpRequest(); 
  } 
  else if (window.ActiveXObject) 
  { 
    oxmlHttp = new ActiveXObject("Microsoft.XMLHttp"); 
  } 
  if(oxmlHttp == null) 
  { 
    alert("Browser does not support XML Http Request"); 
    return; 
  } 
 
  oxmlHttp.onreadystatechange = get_chat_msg_result; 
  oxmlHttp.open("GET","chat_recv_ajax.php",true); 
  oxmlHttp.send(null); 
} 

require_once('dbconnect.php'); 
 
db_connect(); 
 
$sql = "SELECT *, date_format(chatdate,'%d-%m-%Y %r') 
as cdt from chat order by ID desc limit 200"; 
$sql = "SELECT * FROM (" . $sql . ") as ch order by ID"; 
$result = mysql_query($sql) or die('Query failed: ' . mysql_error()); 
 
// Update Row Information 
$msg=""; 
while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) 
{ 
  $msg = $msg . "" . 
    "" . 
    ""; 
} 
$msg=$msg . "<table style="color: blue; font-family: verdana, arial; " . 
 "font-size: 10pt;" border="0"> 
 <tbody><tr><td>" . $line["cdt"] . 
 " </td><td>" . $line["username"] . 
 ": </td><td>" . $line["msg"] . 
 "</td></tr></tbody></table>"; 
 
echo $msg; 
 
数据准备就绪的同时，JavaScript函数会收集来自于PHP接收到的数据。这些数据将被安排置于DIV标签内。oxmlHttp.responseText会保留从PHP程序接收到的聊天消息，并复制到DIV标签的document.getElementById(“DIV_CHAT”).innerHTML属性。 
 
function get_chat_msg_result(t) 
{ 
  if(oxmlHttp.readyState==4 || oxmlHttp.readyState=="complete") 
  { 
    if (document.getElementById("DIV_CHAT") != null) 
    { 
      document.getElementById("DIV_CHAT").innerHTML = oxmlHttp.responseText; 
      oxmlHttp = null; 
    } 
    var scrollDiv = document.getElementById("DIV_CHAT"); 
    scrollDiv.scrollTop = scrollDiv.scrollHeight; 
  } 
}