三个好用的ajax函数实现动态载入页面，可做为局部刷新页面用

    http://www.webshowme.com/04js/content.asp?id=933
1、函数一：
   function ajaxLoader2(id,url) {
        if (document.getElementById) {
            var x = (window.ActiveXObject) ? new ActiveXObject("Microsoft.XMLHTTP") : new XMLHttpRequest();
            }
            if (x)
                {
            x.onreadystatechange = function()
                    {
                if (x.readyState == 4 && x.status == 200)
                        {
                        el = document.getElementById(id);
                        el.innerHTML = x.responseText;
                    }
                    }
                x.open("GET", url, true);
                x.send(null);
                }
        }

2、函数二、利用Iframe来完成
function ajaxLoader(id,url)  {  
    str="<iframe width=\"100%\" height=\"440\" frameborder=\"0\" src=\""+url+"\"></iframe>";
document.getElementById(id).innerHTML=str;
}


3、函数三：与一差不多但是更具体

/***********************************************
* Ajax Page Fetcher- by JavaScript Kit (www.javascriptkit.com)
***********************************************/

var ajaxpagefetcher={
loadingmessage: "<center class=\"errmsg\">Loading Page, please wait...</center>",
exfilesadded: "",

connect:function(containerid, pageurl, bustcache, jsfiles, cssfiles){
var page_request = false
var bustcacheparameter=""
if (window.XMLHttpRequest) // if Mozilla, IE7, Safari etc
page_request = new XMLHttpRequest()
else if (window.ActiveXObject){ // if IE6 or below
try {
page_request = new ActiveXObject("Msxml2.XMLHTTP")
}
catch (e){
try{
page_request = new ActiveXObject("Microsoft.XMLHTTP")
}
catch (e){}
}
}
else
return false
var ajaxfriendlyurl=pageurl.replace(/^http:\/\/[^\/]+\//i, "http://"+window.location.hostname+"/")
page_request.onreadystatechange=function(){ajaxpagefetcher.loadpage(page_request, containerid, pageurl, jsfiles, cssfiles)}
if (bustcache) //if bust caching of external page
bustcacheparameter=(ajaxfriendlyurl.indexOf("?")!=-1)? "&"+new Date().getTime() : "?"+new Date().getTime()
document.getElementById(containerid).innerHTML=decodeURIComponent(ajaxpagefetcher.loadingmessage) //Display "fetching page message"
page_request.open('GET', ajaxfriendlyurl+bustcacheparameter, true)
page_request.send(null)
},

loadpage:function(page_request, containerid, pageurl, jsfiles, cssfiles){
if (page_request.readyState == 4 && (page_request.status==200 || window.location.href.indexOf("http")==-1)){
document.getElementById(containerid).innerHTML=page_request.responseText
for (var i=0; i<jsfiles.length; i++)
this.loadjscssfile(jsfiles[i], "js")
for (var i=0; i<cssfiles.length; i++)
this.loadjscssfile(cssfiles[i], "css")
this.pageloadaction(pageurl) //invoke custom "onpageload" event
}
},

createjscssfile:function(filename, filetype){
if (filetype=="js"){ //if filename is a external JavaScript file
var fileref=document.createElement('script')
fileref.setAttribute("type","text/javascript")
fileref.setAttribute("src", filename)
}
else if (filetype=="css"){ //if filename is an external CSS file
var fileref=document.createElement("link")
fileref.setAttribute("rel", "stylesheet")
fileref.setAttribute("type", "text/css")
fileref.setAttribute("href", filename)
}
return fileref
},

loadjscssfile:function(filename, filetype){ //load or replace (if already exists) external .js and .css files
if (this.exfilesadded.indexOf("["+filename+"]")==-1){ //if desired file to load hasnt already been loaded
var newelement=this.createjscssfile(filename, filetype)
document.getElementsByTagName("head")[0].appendChild(newelement)
this.exfilesadded+="["+filename+"]" //remember this file as being added
}
else{ //if file has been loaded already (replace/ refresh it)
  var targetelement=(filetype=="js")? "script" : (filetype=="css")? "link" : "none" //determine element type to create nodelist using
  var targetattr=(filetype=="js")? "src" : (filetype=="css")? "href" : "none" //determine corresponding attribute to test for
  var allsuspects=document.getElementsByTagName(targetelement)
  for (var i=allsuspects.length; i>=0; i--){ //search backwards within nodelist for matching elements to remove
   if (allsuspects[i] && allsuspects[i].getAttribute(targetattr)!=null && allsuspects[i].getAttribute(targetattr).indexOf(filename)!=-1){
    var newelement=this.createjscssfile(filename, filetype)
    allsuspects[i].parentNode.replaceChild(newelement, allsuspects[i])
   }
}
}
},


pageloadaction:function(pageurl){
this.onpageload(pageurl) //call customize onpageload() function when an ajax page is fetched/ loaded
},

onpageload:function(pageurl){
//do nothing by default
},

load:function(containerid, pageurl, bustcache, jsfiles, cssfiles){
var jsfiles=(typeof jsfiles=="undefined" || jsfiles=="")? [] : jsfiles
var cssfiles=(typeof cssfiles=="undefined" || cssfiles=="")? [] : cssfiles
this.connect(containerid, pageurl, bustcache, jsfiles, cssfiles)
}

} //End object

//Sample usage:
//jaxpagefetcher.load("container_id", "pageurl_or_path", bustcacheBool, [array_of_js_files], [array_of_css_files])
/*

The parameters in that order are:

container_id:    The ID attribute of the DIV or some other container on the page that the Ajax page should load inside
pageurl_or_path: The URL or relative path from the current page to the external page to load. For the URL, it must be from the same domain as the current!
bustcacheBool:A Boolean value (true or false) specifying whether the script should prevent the browser from caching the page after it's been fetched for the 1st time. Set to true if the external page is dynamic and likely changes within the same browser session.
[array_of_js_files]:An optional array that contains the paths to a list of external .js files you wish to load at the same time, each separated by a comma if multiple. For example: ["functions.js", "message.js"].
[array_of_css_files]: An optional array that contains the paths to a list of external .css files you wish to load at the same time, each separated by a comma if multiple. For example: ["pagestyle.js"]

*/
//1) ajaxpagefetcher.load("mydiv", "content.htm", true)
//2) ajaxpagefetcher.load("mydiv2", "content.htm", true, ["external.js"])
//3) ajaxpagefetcher.load("mydiv2", "content.htm", true, ["external.js"], ["external.css"])
//4) ajaxpagefetcher.load("mydiv2", "content.htm", true, ["external.js", "external2.js"])
//5) ajaxpagefetcher.load("mydiv2", "content.htm", true, "", ["external.css", "external2.css"])


/*

<body>
<div id="joe"></div>

<script type="text/javascript">
// Fetch and display "content.htm" inside a DIV automatically as the page loads:
ajaxpagefetcher.load("joe", "content.htm", true)
</script>

<div id="bob"></div>

<script type="text/javascript">
<!-- Fetch and display "sub/content2.htm" inside a DIV when a link is clicked on. Also load one .css file-->
<a href="javascript:ajaxpagefetcher.load('bob', 'sub/content2.htm', false, '', ['page.css'])">Load Content 2</a>
</script>

</body>

*/

注意：使用权用函数一和三的时候，有可能会出现乱码，请将ID对象所在页面的编码改为utf-8编码