好的,我正在尝试制作一个AJAX聊天系统,每400毫秒轮询一次聊天数据库。这部分是工作正常的,但活跃用户列表不行。当我尝试合并这两个请求时,前两个请求会被执行,然后整个过程就会失控,通常定时(12秒)的活跃用户列表请求会开始以每1毫秒更新一次,而第一个请求永远不会再次发生。下面是两个请求的完整AJAX代码:
var waittime=400;chatmsg=document.getElementById("chatmsg");
room = document.getElementById("roomid").value;
chatmsg.focus()
document.getElementById("chatwindow").innerHTML = "loading...";
document.getElementById("userwindow").innerHTML = "Loading User List...";
var xmlhttp = false;
var xmlhttp2 = false;
var xmlhttp3 = false;
function ajax_read(url) {
if(window.XMLHttpRequest){
xmlhttp=new XMLHttpRequest();
if(xmlhttp.overrideMimeType){
xmlhttp.overrideMimeType('text/xml');
}
} else if(window.ActiveXObject){
try{
xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");
} catch(e) {
try{
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
} catch(e){
}
}
}
if(!xmlhttp) {
alert('Giving up :( Cannot create an XMLHTTP instance');
return false;
}
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState==4) {
document.getElementById("chatwindow").innerHTML = xmlhttp.responseText;
setTimeout("ajax_read('methods.php?method=r&room=" + room +"')", waittime);
}
}
xmlhttp.open('GET',url,true);
xmlhttp.send(null);
}
function user_read(url) {
if(window.XMLHttpRequest){
xmlhttp3=new XMLHttpRequest();
if(xmlhttp3.overrideMimeType){
xmlhttp3.overrideMimeType('text/xml');
}
} else if(window.ActiveXObject){
try{
xmlhttp3=new ActiveXObject("Msxml2.XMLHTTP");
} catch(e) {
try{
xmlhttp3=new ActiveXObject("Microsoft.XMLHTTP");
} catch(e){
}
}
}
if(!xmlhttp3) {
alert('Giving up :( Cannot create an XMLHTTP instance');
return false;
}
xmlhttp3.onreadystatechange = function() {
if (xmlhttp3.readyState==4) {
document.getElementById("userwindow").innerHTML = xmlhttp3.responseText;
setTimeout("ajax_read('methods.php?method=u&room=" + room +"')", 12000);
}
}
xmlhttp3.open('GET',url,true);
xmlhttp3.send(null);
}
function ajax_write(url){
if(window.XMLHttpRequest){
xmlhttp2=new XMLHttpRequest();
if(xmlhttp2.overrideMimeType){
xmlhttp2.overrideMimeType('text/xml');
}
} else if(window.ActiveXObject){
try{
xmlhttp2=new ActiveXObject("Msxml2.XMLHTTP");
} catch(e) {
try{
xmlhttp2=new ActiveXObject("Microsoft.XMLHTTP");
} catch(e){
}
}
}
if(!xmlhttp2) {
alert('Giving up :( Cannot create an XMLHTTP instance');
return false;
}
xmlhttp2.open('GET',url,true);
xmlhttp2.send(null);
}
function submit_msg(){
nick = document.getElementById("chatnick").value;
msg = document.getElementById("chatmsg").value;
document.getElementById("chatmsg").value = "";
ajax_write("methods.php?method=w&m=" + msg + "&n=" + nick + "&room=" + room + "");
}
function keyup(arg1) {
if (arg1 == 13) submit_msg();
}
var intUpdate = setTimeout("ajax_read('methods.php')", waittime);
var intUpdate = setTimeout("user_read('methods.php')", waittime);
var waittime=400; chatmsg=…
; 中使用逗号代替分号,这样chatmsg
就成为全局变量了。其他全局变量也是如此(使用var
)。 - Marcel Korpel