Ajax实现评论提交

代码如下：

document.write('<DIV id="loadingg"  style="HEIGHT:65px; WIDTH: 205px;POSITION: absolute; Z-INDEX:1000;border:3px #fff solid;text-align:center; font-size:12px; font-family:Arial, Helvetica, sans-serif;color:#660000;background:#222;opacity:.7;-moz-opacity:.7;filter: alpha(opacity=70); display:none;"><br/><font color="#FF6600"><strong>数据正在读取中,请等候...</strong></font><br/><img src="images/loading.gif"/></DIV>') 
function showloading()  
{ 
var obj=document.getElementById("loadingg") 
if (obj.style.display!="") 
{ 
obj.style.left=((document.documentElement.clientWidth-parseFloat (obj.style.width))/2)+document.documentElement.scrollLeft+"px"; 
obj.style.top=((document.documentElement.clientHeight-parseFloat (obj.style.height))/2)+document.documentElement.scrollTop+"px"; 
obj.style.display=""; 
}else{obj.style.display="none";} 
} 
function $(id) 
{    return document.getElementById(id);    } 
function echo(obj,html){    $(obj).innerHTML=html;} 
function fopen(obj){$(obj).style.display="";} 
function fclose(obj){$(obj).style.display="none";} 
function createxmlhttp(){ 
    var xmlhttp=false; 
    try    { 
          xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); 
     }  
    catch (e) { 
          try { 
               xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); 
          }  
        catch (e) { 
               xmlhttp = false; 
         } 
     } 
    if (!xmlhttp && typeof XMLHttpRequest!='undefined') { 
          xmlhttp = new XMLHttpRequest(); 
                if (xmlhttp.overrideMimeType) {//设置MiME类别 
            xmlhttp.overrideMimeType('text/xml'); 
        } 
    }     
    return xmlhttp;     
} 

function getdata(url,obj1,obj2) 
{        var xmlhttp=createxmlhttp(); 
        if(!xmlhttp) 
        {alert("你的浏览器不支持XMLHTTP！！"); 
            return; 
        } 
        showloading()  
        xmlhttp.onreadystatechange=requestdata; 
        xmlhttp.open("GET",url,true); 
        xmlhttp.send(null); 
        function requestdata() 
        {        fopen(obj1); 
                //echo(obj1,"正在加载数据，请稍等......"); 
                //alert(xmlhttp.readyState) 
                if(xmlhttp.readyState==4) 
                {    if(xmlhttp.status==200) 
                    {    if(obj1!=obj2){fclose(obj1);}; 
                        echo(obj2,xmlhttp.responseText); 
                        showloading()  
                    } 
                }             
        } 
} 
function postdata(url,obj,data) 
{       var rnd=Math.random() 
        var xmlhttp=createxmlhttp(); 
        if(!xmlhttp) 
        { 
            alert("你的浏览器不支持XMLHTTP！！"); 
            return; 
        } 
        showloading()  
        xmlhttp.open("POST", url, true); 
        xmlhttp.onreadystatechange=requestdata; 
        xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); 
        xmlhttp.send(data); 
        function requestdata() 
        {    fopen(obj); 
            echo(obj,"正在提交数据，请稍等......"); 
            if(xmlhttp.readyState==4) 
            {    if(xmlhttp.status==200) 
                { 
                    echo(obj,xmlhttp.responseText); 
                    reget(rnd); 
                    setTimeout("echo('showresult','')",2000); 
                    echo('Message','') 
                    showloading()  
                } 
            } 
        } 
} 
function lTrim(str) 
{ 
  if (str.charAt(0) == " ") 
  { 
    //如果字串左边第一个字符为空格 
    str = str.slice(1);//将空格从字串中去掉 
    //这一句也可改成 str = str.substring(1, str.length); 
    str = lTrim(str);    //递归调用 
  } 
  return str; 
} 

//去掉字串右边的空格 
function rTrim(str) 
{ 
  var iLength; 

  iLength = str.length; 
  if (str.charAt(iLength - 1) == " ") 
  { 
    //如果字串右边第一个字符为空格 
    str = str.slice(0, iLength - 1);//将空格从字串中去掉 
    //这一句也可改成 str = str.substring(0, iLength - 1); 
    str = rTrim(str);    //递归调用 
  } 
  return str; 
} 

//去掉字串两边的空格 
function trim(str) 
{ 
  return lTrim(rTrim(str)); 
} 

function f(obj) 
{ 
    return trim(eval("document.ajax_post."+obj+".value")); 
    //return trim($(obj).value); 
} 

function SaveReply() 
{    if(f("username")=="") 
    {    alert("请填写用户名"); 
        return false; 
    } 
    if(f("Message")=="") 
    {    alert("内容不可榭"); 
        return false; 
    } 
    var validate,password,log_DisKey=0,log_DisURL=0,log_DisSM=0 
    validate="" 
    password="" 
    if(document.ajax_post.log_DisKey.checked){ 
        log_DisKey=f("log_DisKey") 
        } 
    if(document.ajax_post.log_DisURL.checked){ 
        log_DisURL=f("log_DisURL") 
        } 
    if(document.ajax_post.log_DisSM.checked){ 
        log_DisSM=f("log_DisSM") 
        } 
    if((typeof eval(document.ajax_post.validate))!="undefined"){ 
        if(f("validate")=="") 
        {    alert("请填写验证码"); 
            return false; 
        }else{ 
            validate=f("validate"); 
        } 
    }     
    if((typeof eval(document.ajax_post.password))!="undefined"){ 
        password=f("password"); 
    } 
    data="username="+escape(f("username"))+"&password="+escape(password)+"&validate="+escape(validate)+"&log_DisSM="+escape(log_DisSM)+"&log_DisURL="+escape(log_DisURL)+"&log_DisKey="+escape(log_DisKey)+"&Message="+escape(f("Message"))+"&logID="+escape(f("logID"))+"&action="+escape(f("action")); 
    //alert(data); 
    postdata("wbc_blogcomm.asp","showresult",data); 
    return true; 
}