http://web.pts.org.tw/php/include/ajax.js

1function initReq(reqType,url,bool){
2
3    try{
4
5        /* Specify the function that will handle the 
6
7        HTTP response */
8
9        request.open(reqType,url,bool);    
10        request.onreadystatechange=handleResponse;
11        
12        if(reqType.toLowerCase() == "post") {
13            request.setRequestHeader("Content-Type",
14                        "application/x-www-form-urlencoded; charset=UTF-8");
15            request.send(arguments[3]);
16        } else {
17            request.send(null);
18        }
19    } catch (errv) {
20
21        alert(
22
23                "The application cannot contact the server "+
24
25                "at the moment. "+
26
27                "Please try again in a few seconds."+errv.message );
28
29    }
30
31}
32
33/* Wrapper function for constructing a request object.
34
35 Parameters:
36
37  reqType: The HTTP request type, such as GET or POST.
38
39  url: The URL of the server program.
40
41  asynch: Whether to send the request asynchronously or not. */
42
43function httpRequest(reqType,url,asynch){
44
45    //Mozilla-based browsers
46
47    if(window.XMLHttpRequest){
48
49        request = new XMLHttpRequest(  );
50
51    } else if (window.ActiveXObject){
52
53        request=new ActiveXObject("Msxml2.XMLHTTP");
54
55        if (! request){
56
57            request=new ActiveXObject("Microsoft.XMLHTTP");
58
59        }
60
61     }
62
63    //the request could still be null if neither ActiveXObject
64
65    //initialization succeeded
66
67    if(request){
68
69       
70       
71        if(reqType.toLowerCase() != "post") {
72            initReq(reqType,url,asynch);
73        }  else {
74            //the POSTed data
75            var args = arguments[3];
76            if(args != null && args.length > 0){
77                initReq(reqType,url,asynch,args);
78            }
79        }
80    } else {
81
82        alert("Your browser does not permit the use of all "+
83
84              "of this application's features!");}
85
86}