http://www.laboratorioadolescenza.org/iwetc/res/js/ajax.js?v=2

1function IwAjax() {
2  this.window=window;
3  this.debugReqNotReady=false;
4  this.debugReqError=false;
5  this.debugReqOk=false;
6}
7IwAjax.prototype.newRequest = function() {
8	var req = null;
9  // branch for native XMLHttpRequest object
10  if (this.window.XMLHttpRequest) {
11    try {
12      req = new XMLHttpRequest();
13    } catch(e) {
14      req = null;
15    }
16  // branch for IE/Windows ActiveX version
17  } else if (this.window.ActiveXObject) {
18    try {
19      req = new ActiveXObject("Msxml2.XMLHTTP");
20    } catch(e) {
21      try {
22        req = new ActiveXObject("Microsoft.XMLHTTP");
23      } catch(e) {
24        req = null;
25      }
26    }
27  }
28  return req;
29}
30IwAjax.prototype.loadXmlDoc = function(url,listener) {
31  var ajax=this;
32  var req=this.newRequest()
33  if (req!=null) {
34    if (listener!=null) {
35      req.onreadystatechange = function() {
36        listener.processReqChange(req);
37      }
38    } else {
39      req.onreadystatechange = function() {
40        ajax.processReqChange(req);
41      }
42    }
43    req.open("GET", url, true);
44		req.send("");
45  }
46}
47IwAjax.prototype.processReqChange = function(req) {
48  if (req.readyState==4) {
49    if (req.status==200) {
50      this.processReqOk(req);
51    } else {
52      this.processReqError(req);
53    }
54  } else {
55    this.processReqNotReady(req);
56  }
57}
58IwAjax.prototype.processReqNotReady = function(req) {
59  if (this.debugReqNotReady) {
60    alert("req.readyState="+req.readyState);
61  }
62}
63IwAjax.prototype.processReqError = function(req) {
64  if (this.debugReqError) {
65    var s="";
66    s+="req.readyState="+req.readyState+"\n";
67    s+="req.status="+req.status+"\n";
68    s+="req.statusText="+req.statusText+"\n";
69    alert(s);
70  }
71}
72IwAjax.prototype.processReqOk = function(req) {
73  if (this.debugReqOk) {
74    var s="";
75    s+="req.readyState="+req.readyState+"\n";
76    s+="req.status="+req.status+"\n";
77    s+="req.statusText="+req.statusText+"\n";
78    s+="req.responseXML="+req.responseXML+"\n";
79    s+="req.responseText="+req.responseText+"\n";
80    alert(s);
81  }
82}
83IwAjax.prototype.newReqListener = function(reqOk,reqError,reqNotReady) {
84  return new IwAjaxReqListener(this,reqOk,reqError,reqNotReady);
85}
86// listener
87function IwAjaxReqListener(ajax,reqOk,reqError,reqNotReady) {
88  this.ajax=ajax;
89  this.processReqOk=reqOk;
90  this.processReqError=reqError;
91  this.processReqNotReady=reqNotReady;
92}
93IwAjaxReqListener.prototype.processReqChange = function(req) {
94  if (req.readyState==4) {
95    if (req.status==200) {
96      if (this.processReqOk!=null) {
97        this.processReqOk(req,this);
98      } else {
99        this.ajax.processReqOk(req);
100      }
101    } else {
102      if (this.processReqError!=null) {
103        this.processReqError(req,this);
104      } else {
105        this.ajax.processReqError(req);
106      }
107    }
108  } else {
109    if (this.processReqNotReady!=null) {
110      this.processReqNotReady(req,this);
111    } else {
112      this.ajax.processReqNotReady(req);
113    }
114  }
115}