AJAX操作的JS类
最近用AJAX开始的时候是用网上下载的一个ajax.dll，但是似乎它不是异步处理的，应该有什么开关的吧，没找到文档，我也没研究，反正这东西也不难，就自己用js写了一个，呵呵，有兴趣的朋友看一下

///AJAX实现类
///acheqi 2005-12-3
function Js_Ajax()
{
this.PostUrl; ///AJAX提交的文件地址
this.Treat; ///参数返回后的处理过程

this.GetXmlHttpRequest=function()
{
var req;
if (window.XMLHttpRequest)
{ // Mozilla, Safari,...
        req = new XMLHttpRequest();
        if (req.overrideMimeType) {
          req.overrideMimeType('text/xml');
        }
    } else if (window.ActiveXObject) { // IE
        try {
          req = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
          try {
            req = new ActiveXObject("Microsoft.XMLHTTP");
          } catch (e) {}
        }
    }

if (!req)
{
  alert("JS_CLASS:ERROR:组件创建失败")
  return false;
}
return req;
}

this.SendRequest=function(url, params, HttpMethod)
{
if (!HttpMethod)
{
    HttpMethod = "POST";
  }
  var Obj=this.GetXmlHttpRequest();
  var s=this.processChech(Obj,this.Treat)
  Obj.onreadystatechange = s
  Obj.open(HttpMethod, url, true);
    Obj.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    Obj.send(params);
}

this.Creat=function()
{
this.SendRequest(this.PostUrl,null,"GET")
}

this.processChech=function(mobject,f)
{
return function()
{
  if (mobject.readyState == 4)
  {    
  var state=mobject.status;
  if (state==404)
  {
  alert("JS_CLASS:ERROR:请求页面不存在");
  return false;  
  }
  else if(state<200)
  {
  alert("JS_CLASS:ERROR:客户端错误:"+state.statusText);
  return false;
  }
  else if(state==200)
  {
  f(mobject.responseText);
  //return false;
  }
  }
 
}

}
}
var Ajax=new Js_Ajax();

调用方法

this.MemberEmail;

this.EmailValid=false;
this.NameValid=false;

/*检查email是否已经被注册*/
this.RequestMailIsReg=function(RequestData)
{
if (RequestData)
{
  this.EmailValid=true;
}
else
{
  this.EmailValid=false;
}
}
this.ClickEmailIsReg=function(Email)
{
this.MemberEmail=Js_System.prototype.GetItem(Email);
//alert(this.MemberEmail);
//检查格式是否正确
if (Js_String.prototype.ClickEmail(this.MemberEmail)==false)
{
  return false;
}
else
{
  Ajax.PostUrl="MemberReg.Aspx?Action=AjaxChk&Type=ChkEmail&Email="+this.MemberEmail;
  Ajax.Treat=this.RequestMailIsReg;
  Ajax.Creat();
  if (this.EmailValid)
  {
  Js_String.prototype.ErrorStr='Email已经被注册！';
  return false;
  }
  else
  {
  return true;
  }
}
}
/*检查email是否已经被注册End*/