//重构XMLHttpRequest
var net = new Object();  //名字空間對象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;net.ContentLoader = function(url, onl oad, one rror) {   //構造函數    this.url = url;    this.req = null;    this.onload = onl oad;    this.onerror = (onerror) ? one rror : this.defaultError;    this.loadXMLDoc(url);}net.ContentLoader.prototype = {    loadXMLDoc: function(url) {  //重新命名的initXMLHttpRequest函數        if (window.XMLHttpRequest) {   //重構過的loadXML函數            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() {                    loader.onReadyState.call(loader);                }                this.req.open(‘GET‘, url, true); //重構過的sendRequest函數                this.req.send(null);            } catch (err) {                this.onerror.call(this);            }        }    },    onReadyState: function() {  //重構過的回調函數        var req = this.req;        var ready = req.readyState;        if (ready == net.READY_STATE_COMPLETE) {            var httpStatus = req.status;            if (httpStatus == 200 || httpStatus == 0) {                this.onload.call(this);            } else {                this.onerror.call(this);            }        }    },    defaultError: function() {        alert("error fetching data!"        + "\n\nreadyState:" + this.req.readyState        + "\nstatus:" + this.req.status        + "\nheaders:" + this.req.getAllResponseHeaders());    }}function myCallBack() {     alert{this.url    +" loaded! Here‘s the content:\n\n"    +this.req.responseText};}