if(xhr.status==200||xhr.status==0){
alert('ok');
}

showbo>
item>1item>
item>2item>
item>3item>
item>4item>
/showbo>

function getajax(){
if(window.XMLHttpRequest)return new XMLHttpRequest();
else if(window.ActiveXObject)return new ActiveXObject("microsoft.xmlhttp");
}
var xhr=getajax();
xhr.onreadystatechange=function(){
if(xhr.readyState==4){
if(xhr.status==200||xhr.status==0){
var doc=xhr.responseXML,item=doc.getElementsByTagName("item");
alert(item.length);//在ie輸出為0，在ff下為4。似乎在ie下未生成xml的樹結(jié)構(gòu)，具體原因要問ms了。。
}
else alert('發(fā)生錯(cuò)誤\n\n'+xhr.status);
}
}
xhr.open("get","showbo.xml?_dc="+new Date().getTime(),true);
xhr.send(null);

xhr.onreadystatechange=function(){
if(xhr.readyState==4){
if(xhr.status==200||xhr.status==0){
var doc=xhr.responseXML;
if(document.allxhr.status==0){//為ie并且直接托進(jìn)瀏覽器的時(shí)重構(gòu)xml的樹結(jié)構(gòu)
doc=new ActiveXObject("microsoft.xmldom");
doc.loadXML(xhr.responseText);
doc=doc.documentElement;
}
var item=doc.getElementsByTagName("item");
alert(item.length);
}
else alert('發(fā)生錯(cuò)誤\n\n'+xhr.status);
}
}

'防止asp使用utf-8編碼時(shí)中文出現(xiàn)亂碼
Session.CodePage=65001
Response.CharSet="utf-8"

globalization requestEncoding="gb2312" responseEncoding="gb2312"/>

function callServerByPost(url,data,fun) {
var http_request=null;
if (window.ActiveXObject)http_request = new ActiveXObject("Microsoft.XMLHTTP");
}else if (window.XMLHttpRequest) http_request = new XMLHttpRequest();
if (!http_request) {
alert('Giving up :Cannot create an XMLHTTP instance');
return false;
}
http_request.onreadystatechange = fun;
http_request.open("POST", url, true);
http_request.setrequestheader("Content-length",data.length);
http_request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
http_request.send(data);//傳送資料
}
function ajax_post(url,data) {
url=url+"?t="+new Date();
callServerByPost(url,data,function fns(){
if(http_request.readyState == 4) {
if (http_request.status == 200) {
return http_request.responseText;//在這里明明調(diào)試時(shí)http_request.responseText已經(jīng)有值但是在外邊卻接收不到
} else {
alert("你請(qǐng)求數(shù)據(jù)有錯(cuò)");
}
}
});
}
function getData(){
var url="ajax_server.aspx";
var data="name=ljppwd=ljp";
var t=ajax_post(url,data);
alert(t);//在這里彈出undefined =============================
}

function callServerByPost(url,data,fun) {
var http_request=null;
if (window.ActiveXObject)http_request = new ActiveXObject("Microsoft.XMLHTTP");
}else if (window.XMLHttpRequest) http_request = new XMLHttpRequest();
if (!http_request) {
alert('Giving up :Cannot create an XMLHTTP instance');
return false;
}
// http_request.onreadystatechange = fun; //為同步時(shí)不再需要處理函數(shù)了。。。。。。。
http_request.open("POST", url, false);//改為同步
http_request.setrequestheader("Content-length",data.length);
http_request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
http_request.send(data);//傳送資料
return http_request.responseText;//同步時(shí)可以直接返回，因?yàn)闀?huì)阻止其他的代碼執(zhí)行
}
function ajax_post(url,data) {
url=url+"?t="+new Date();
return callServerByPost(url,data,null);//不需要傳遞回調(diào)，并且直接返回callServerByPost的返回值
}
function getData(){
var url="ajax_server.aspx";
var data="name=ljppwd=ljp";
var t=ajax_post(url,data);
alert(t);//這里就不會(huì)輸出undefined了。。。。。。。。。。。。,不過如果網(wǎng)路慢的話，瀏覽器就假死了。。
}

String.prototype.trim=function(){return this.replace(/$\s*|\s*$/g,'');}
var Showbo={author:'showbo'};
//獲取json對(duì)象
Showbo.getJson=function(v){if(typeof(v)=='string')return eval('('+v+')');else return v;}
//根據(jù)id獲取對(duì)象
Showbo.$=function(Id){if('object'==typeof(Id))return Id;else if('string'==typeof(Id))return document.getElementById(Id);else return null;}
Showbo.IsIE=!!document.all;
//擴(kuò)展IE下的XMLHttpRequest
if(Showbo.IsIE!window.XMLHttpRequest)window.XMLHttpRequest=function(){
var acX=['msxml2.xmlhttp.5.0','msxml2.xmlhttp.4.0','msxml2.xmlhttp.3.0','msxml2.xmlhttp','microsoft.xmlhttp'],Xhr;
for(var i=0;itry{Xhr=new ActiveXObject(acX[i]);return Xhr;}catch(e){}
return false;
}
//ajax應(yīng)用池
Showbo.Ajax={
pools:[]//存儲(chǔ)ajax對(duì)象的數(shù)組
,getObject:function(){//從數(shù)組中獲取ajax對(duì)象，如果未返回則新建一個(gè)ajax對(duì)象
for(var i=0;ithis.pools.length;i++)
if(this.pools[i].readyState==0||this.pools[i].readyState==4)return this.pools[i];
this.pools[this.pools.length]=new XMLHttpRequest();
return this.pools[this.pools.length-1];
}
,send:function(cfg){/*cfg示例
{
url:'請(qǐng)求的頁(yè)面'
,params:'鍵值對(duì)，注意不是json對(duì)象'
,method:'post/get，如果為指定則默認(rèn)為get'
,success:成功時(shí)的回調(diào)函數(shù)
,failure:失敗時(shí)的回調(diào)函數(shù)
,otherParams:提供給回調(diào)函數(shù)的其他參數(shù)，可以為json對(duì)象
}
成功或者失敗的回調(diào)函數(shù)參數(shù)為 (當(dāng)前的xhr對(duì)象，配置文件的中的otherParams)
*/
if(!cfg||!cfg.url)throw("未設(shè)置配置文件！");
var method=cfg.method,asy="boolean"==typeof(cfg.asy)?cfg.asy:true;
if(!method||method!="post")method="get";
if(method.toLocaleLowerCase()=='get'){
var _dc=new Date().getTime();//加時(shí)間戳防止ie瀏覽器下的緩存
cfg.params=cfg.params?cfg.params+'_dc='+_dc:'_dc='+_dc;
if(cfg.url.indexOf("?")!=-1)cfg.url+=""+cfg.params;
else cfg.url+="?"+cfg.params;cfg.params=null;
}
else if(!cfg.params)cfg.params='';
var o=this.getObject();
if(!o)throw("未能創(chuàng)建ajax對(duì)象！");
o.open(method,cfg.url,asy);
if(method.toLocaleLowerCase()=='post')o.setRequestHeader("content-type","application/x-www-form-urlencoded");
o.send(cfg.params);
o.onreadystatechange=function(){
if(o.readyState==4){
if(o.status==200||o.status==0){
if("function"==typeof(cfg.success))cfg.success(o,cfg.otherParams);
}
else if("function"==typeof(cfg.failure))cfg.failure(o,cfg.otherParams);
}
}
}
}