Javascript load Page,load css,load js实现代码

/*********************************************** 
* Ajax Page Fetcher- by JavaScript Kit (www.javascriptkit.com) 
***********************************************/ 
var ajaxpagefetcher={ 
loadingmessage: "Loading Page, please wait...", 
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=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: 
//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"])