// Chatr - Super-simple chat for your site
// (c) 2006 David Sterry
// Distributed under the BSD license
// Link: http://www.sterryit.com/chatr
// Global variables
var isFirefox;
var isIE;
var timeout;
var pingtimeout;
var textFocus = true;
var starsadded = false;
var md4hash = 0;
var timedout = 0;
var pingsent = 0;
var requestsent = 0;
var postsent = 0;
var chatsent = 0;
var pingRate = 1000 * 10; // 30 seconds
var refreshRate = 1000 * 2; // two seconds
var rnd = Math.random(); // random seed
// added to reduce server load
var t = 0;
var update_period = 3;
var throttle_back = 60; // this is in multiples of refreshRate
var lastpost = 0; // throttling reduces traffic by
//
// Get an XMLHttpRequest object
//
function getAjax() {
var xmlhttp;
if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
try {
xmlhttp = new XMLHttpRequest();
} catch (e) {
xmlhttp = false;
}
}
return xmlhttp;
}
//
// Get browser type
//
function sniff() {
var ff = "Netscape";
var ie = "Microsoft Internet Explorer";
isFirefox = ( navigator.appName == ff );
isIE = (navigator.appName == ie );
}
// Capture the enter key on
// the input box and initiate a
// GET to the post url
//
function captureReturn( event )
{
if( isIE ) {
event = window.event;
}
//
// Supress event bubbling
//
if( event.keyCode == 13 ) {
//
// fetch the feed
//
postText();
if( isIE ) {
event.returnValue = false;
} else {
event.preventDefault();
}
}
}
//
// Auto scroll the chat window
// if the text exceeds the div
//
function scrollChatPane()
{
pane = document.getElementById( "chatpane" );
while( pane.scrollTop < pane.scrollHeight - pane.offsetHeight )
{
pane.scrollTop = pane.scrollTop + 10;
}
}
//
// Show the little loading animation
// when the page starts
//
function showLoadScreen()
{
var loading = "Lade Chat-Daten...
";
chat = document.getElementById( "chatbuffer" );
user = document.getElementById( "userlist" );
chat.innerHTML = loading;
user.innerHTML = loading;
}
//
// ping the server to let
// it know we're still alive
//
function resetPing()
{
pingtimeout = window.setTimeout( "pingServer()", pingRate );
}
//
// Start the fetch timer to update
// the chatpane and userlist
//
function setTimers()
{
timeout = window.setTimeout( "fetch()", refreshRate );
}
//
// Start the async fetch
// and reset the fetch timer
//
function fetch()
{
window.clearTimeout( timeout );
fetchBufferText();
if(t++ % update_period) {
fetchUserList();
}
if( t - lastpost > throttle_back ) {
// alert("throttled t=" + t + " lastpost="+lastpost);
refreshRate = 5000;
update_period = 2;
} else {
// alert("not throttled");
refreshRate = 2000;
update_period = 3;
}
if( timedout != 1 ) { setTimers(); }
}
/* #############################
*
* function: fetchUserList()
* purpose:
*
* This function retrieves the userlist.
* The userlist is returned as a set of
* list-items from the server. The existing
* list is replaced and the new list is rendered
* between two tags. This function will
* call to update the chat buffer when it completes.
*
* notes: A random number is generated
* when this page loads. This number is
* incrimented and appended to the url to
* prevent caching problems in IE
*
* #############################
*/
function fetchUserList()
{
rnd++;
url = 'userlist.php?' + rnd;
req = getAjax();
req.onreadystatechange = function(){
if( req.readyState == 4 && req.status == 200 ) {
obj = document.getElementById( "userlist" );
obj.innerHTML = req.responseText;
fetchBufferText();
}
}
req.open( 'GET', url, true );
req.send( null );
requestsent++;
}
/* #############################
*
* function: fetchBufferText()
* purpose:
*
* This function retrieves the last
* twenty lines of the chat buffer.
* The chat buffer is returned as a
* set of list-items and are rendered
* in a tag. This function calls
* the scroll function to scroll the
* chat pane.
*
* notes: A random number is generated
* when this page loads. This number is
* incrimented and appended to the url to
* prevent caching problems in IE
*
* #############################
*/
function fetchBufferText()
{
user = location.search.substring( 1, location.search.length );
url = 'message.php?u=' + user + '&rand=' + rnd;
req = getAjax();
req.onreadystatechange = function(){
if( req.readyState == 4 && req.status == 200 ) {
obj = document.getElementById( "chatbuffer" );
obj.innerHTML = req.responseText;
var timeoutstring = user + "timeout";
if( obj.innerHTML.indexOf(timeoutstring) != -1 ) {
obj.innerHTML = obj.innerHTML.replace(timeoutstring,"");
timedout = 1;
}
scrollChatPane();
}
}
req.open( 'GET', url , true );
req.send( null );
requestsent++;
//changeTitle(); // this doesn't work
}
/* #############################
*
* function: postText()
* purpose:
*
* A users chat is posted to the server in
* the querystring of the posttext.aspx url.
* The format of the querystring is:
*
* ?u=[username]&t=[chat text]
*
* Because of the nature of the url encoding
* certain chat text will fail to post.
* The chat text cannot contain any values
* that are invalid in a url, or are part
* of the url structure, such as the ampersand (&)
* forward slash (/), etc.
*
* #############################
*/
function postText()
{
chatbox = document.getElementById( "mytext" );
chat = escape(chatbox.value);
chatbox.value = '';
if(chat.length == 0 ) {return; }
user = location.search.substring( 1, location.search.length );
url = 'posttext.php?u=' + user + '&rand=' + rnd + '&t=' + chat ;
req = getAjax();
req.onreadystatechange = function(){
if( req.readyState == 4 && req.status == 200 ) {
fetch();
}
}
req.open( 'GET', url, true );
req.send( null );
lastpost = t;
postsent++;
}
/* #############################
*
* function: pinServer()
* purpose:
*
* A sends a message to the server indicating
* the browser is still open and the user is
* still alive.
*
* #############################
*/
function pingServer()
{
window.clearTimeout( pingtimeout );
user = location.search.substring( 1, location.search.length );
url = 'ping.php?u=' + user + '&rand=' + rnd;
req = getAjax();
req.open( 'GET', url, true );
req.send( null );
pingsent++;
if(timedout != 1) {
resetPing();
}
}
function startChat()
{
sniff();
pingServer();
showLoadScreen();
setTimers();
resetPing();
if( isFirefox ) {
mytext = document.getElementById( "mytext" );
}
mytext.focus();
mytext.onkeypress = captureReturn;
}