重構這個概念在Ajax中尤為重要，好的重構可以在大量Javascript代碼的情況下更好的降低代碼的混亂性，使其更加清晰。下面的ContentLoader對象正是一個很好的范例
/**//*
url-loading?object?and?a?request?queue?built?on?top?of?it
*/
/**//*?namespacing?object?*/
var?net=new?Object();
net.READY_STATE_UNINITIALIZED=0;
net.READY_STATE_LOADING=1;
net.READY_STATE_LOADED=2;
net.READY_STATE_INTERACTIVE=3;
net.READY_STATE_COMPLETE=4;
/**//*---?content?loader?object?for?cross-browser?requests?---*/
net.ContentLoader=function(url,onload,onerror,method,params,contentType)
{
??this.req=null;
??this.onload=onload;
??this.onerror=(onerror)???onerror?:?this.defaultError;
??this.loadXMLDoc(url,method,params,contentType);
}
net.ContentLoader.prototype.loadXMLDoc=function(url,method,params,contentType){
??if?(!method){
????method="GET";
??}
??if?(!contentType?&&?method=="POST"){
????contentType='application/x-www-form-urlencoded';
??}
??if?(window.XMLHttpRequest){
????this.req=new?XMLHttpRequest();
??}?else?if?(window.ActiveXObject){
????this.req=new?ActiveXObject("Microsoft.XMLHTTP");
??}
??if?(this.req){
????try{
??????var?loader=this;
??????this.req.onreadystatechange=function(){
????????net.ContentLoader.onReadyState.call(loader);
??????}
??????this.req.open(method,url,true);
??????if?(contentType){
????????this.req.setRequestHeader('Content-Type',?contentType);
??????}
??????this.req.send(params);
????}catch?(err){
??????this.onerror.call(this);
????}
??}
}
net.ContentLoader.onReadyState=function(){
??var?req=this.req;
??var?ready=req.readyState;
??var?httpStatus=req.status;
??if?(ready==net.READY_STATE_COMPLETE){
????if?(httpStatus==200?||?httpStatus==0){
??????this.onload.call(this);
????}else{
??????this.onerror.call(this);
????}
??}
}
net.ContentLoader.prototype.defaultError=function(){
??alert("error?fetching?data!"
????+"\n\nreadyState:"+this.req.readyState
????+"\nstatus:?"+this.req.status
????+"\nheaders:?"+this.req.getAllResponseHeaders());
}