当前文件： AjaxChat/js/AjaxFunctions.js[3K，2009-6-12 11:31:35]，打开代码结构图

		            
  1//Global variables
  2var timeID;
  3var refreshRate = 2000; // two seconds
  4var rnd = Math.random();
  5
  6var isFirefox;
  7var isIE;
  8
  9//var XmlHttp;
 10var AjaxServerPageName;
 11AjaxServerPageName = "Server.aspx";
 12
 13//Creating and setting the instance of appropriate XMLHTTP Request object to a 揦mlHttp?variable  
 14function getAjax()
 15...{
 16    var XmlHttp;
 17    
 18    //Creating object of XMLHTTP in IE
 19    try
 20    ...{
 21        XmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
 22    }
 23    catch(e)
 24    ...{
 25        try
 26        ...{
 27            XmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
 28        } 
 29        catch(oc)
 30        ...{
 31            XmlHttp = null;
 32        }
 33    }
 34    //Creating object of XMLHTTP in Mozilla and Safari 
 35    if(!XmlHttp && typeof XMLHttpRequest != "undefined") 
 36    ...{
 37        XmlHttp = new XMLHttpRequest();
 38    }
 39    return XmlHttp;
 40}
 41
 42// Get browser type
 43function sniffBrowserType() ...{
 44    isFirefox = ( navigator.appName == "Netscape" );
 45    isIE = (navigator.appName == "Microsoft Internet Explorer" ); 
 46}
 47
 48
 49// Capture the enter key on the input box and post message
 50function captureReturn( event )
 51...{
 52    if(event.which || event.keyCode)
 53    ...{
 54        if ((event.which == 13) || (event.keyCode == 13)) 
 55        ...{
 56            postText();
 57            return false;
 58        }
 59        else ...{
 60            return true;
 61        }
 62    }    
 63}
 64
 65// Start the update timer
 66function setTimers()
 67...{
 68    timeID = window.setTimeout( "updateAll()", refreshRate );
 69}
 70
 71// Start to update and reset the update timer
 72function updateAll()
 73...{
 74    window.clearTimeout( timeID );
 75    getUserList();
 76    setTimers();
 77}
 78
 79function getUserList()
 80...{
 81    rnd++;
 82    url = 'Server.aspx?action=UserList&session=' + rnd;
 83    req = getAjax();
 84
 85    req.onreadystatechange = function()...{
 86    
 87        if( req.readyState == 4 && req.status == 200 ) ...{
 88        
 89            obj = getElement( "userlist" );
 90            obj.innerHTML = req.responseText;
 91            getBufferText();
 92        }
 93    
 94    }
 95    
 96    req.open( 'GET', url, true );
 97    req.send( null );
 98}
 99
100function getBufferText()
101...{
102    rnd++;
103    url = 'Server.aspx?action=GetMsg&session=' + rnd;
104    req = getAjax();
105    
106    req.onreadystatechange = function()...{
107    
108        if( req.readyState == 4 && req.status == 200 ) ...{
109        
110            obj = getElement( "chatbuffer" );
111            obj.innerHTML = req.responseText;
112            scrollChatPane();
113            //FocusWindow();
114        }
115    }
116    
117    req.open( 'GET', url , true );
118    req.send( null );
119}
120
121function postText()
122...{
123    rnd++;
124    chatbox = getElement( "mytext" );
125    chat = chatbox.value;
126    chatbox.value = "";
127    
128    userid = location.search.substring( 1, location.search.length );
129    url = 'Server.aspx?action=PostMsg&u=' + userid + '&t=' + encodeURIComponent(chat) + '&session=' + rnd;
130    
131    req = getAjax();
132    
133    req.onreadystatechange = function()...{
134    
135        if( req.readyState == 4 && req.status == 200 ) ...{
136            updateAll();
137        }
138    
139    }
140    
141    req.open( 'GET', url, true );
142    req.send( null );
143}
144
145function getElement( id ) 
146...{
147    if( isIE ) ...{
148        return document.all[ id ];
149    }
150    else ...{
151        return document.getElementById( id );
152    }
153}
154
155function showLoadScreen()
156...{
157    var loading = "<div style=\"text-align:center;color:red;\"><h5>Loading...</h5></div>";
158
159    chat = getElement( "chatbuffer" );
160    chat.innerHTML = loading;
161    
162    user = getElement( "userlist" );
163    user.innerHTML = loading;
164}
165
166function scrollChatPane()
167...{
168    var obj = document.getElementById("chatpane");
169    obj.scrollTop = obj.scrollHeight;
170}
171
172function setFocus(ControlName)
173...{
174    var control = document.getElementById(ControlName);
175    if( control != null )
176    ...{
177        control.focus();
178    }
179}
180function FocusWindow()
181...{
182
183    //TODO: FireFox doesn't work?
184    window.focus();
185
186}