html>
 head>
  title>Ajax实例/title>
  script src="ajax3.0.js">/script>
 /head> 
 body>
  script>
   document.write(new Date()+"br>");
   document.write(new Date()+"br>");
   document.write(new Date()+"br>");
  /script> 
  div id="show" style="background:yellow;border:1px solid blue">
   内容加载中..... 
  /div>
  script>
   function read() {
    Ajax().get("read.php?num="+Math.random(), function(data){
     document.getElementById("show").innerHTML=data;   
    }) 
   }
   read();
   setInerval("read()",3000);
   function send() {
    var username=document.frm.username;
    var desn=document.frm.desn;
    var datao = {username:username.value, desn:desn.value};
    Ajax().post("save.php", datao, function(data){
      
      read();
      username.value="";
      desn.value="";
    });
   }
  /script>
  form name="frm">
   用户名:input type="text" name="username" value="">br>
   内容: textarea cols="40" rows="5" name="desn">/textarea>
   input type="button" onclick="send()" value="留言">
  /form>
  script>
   document.write(new Date()+"br>");
   document.write(new Date()+"br>");
   document.write(new Date()+"br>");
  /script>
 /body>
/html> 

//read.php
 @readfile("demo.txt");
//save.php
// header("Content-Type:text/html;charset=gb2312")
 $username=$_POST["username"];
 $desn = $_POST["desn"];

 $fh = fopen("demo.txt", "a");

 $text=$username."--".date("Y-m-d H:i:s")."说:".$desn."br>";

 fwrite($fh, $text);

 fclose($fh);
//demo.text
fdsafdsa--2012-11-01 12:24:04说:fdsafdsabr>fdsafdsa--2012-11-01 12:24:07说:fdsafdsafsabr>111--2012-11-01 12:25:07说:2222br>eeee--2012-11-01 12:25:10说:eeeebr>fdsfds--2012-11-01 12:25:12说:fdsfdsfdsbr>fdsfds--2012-11-01 12:25:19说:fdsfdsfsbr>fdsfdsf--2012-11-01 12:25:22说:sfdsfdsfdsbr>fdsafdsa--2012-11-01 12:26:00说:fdsafdsabr>