Ciekawe - AHAH -implementacja Ajax.
Jak uruchomić kod przesłany z serwera w czasie wymiany Ajax
To wszystko bazuje na pomyśle JAH (JavaScript Ascynchronous HTML)
Receive AHAH Request
function ahahDone(target) {
// only if req is "loaded"
if (req.readyState == 4) {
// only if "OK"
if (req.status == 200 || req.status == 304) {
results = req.responseText;
document.getElementById(target).innerHTML = results;
} else {
document.getElementById(target).innerHTML="ahah error:n" +
req.statusText;
}
}
}

Other than error checking, the only real work done is:
document.getElementById(target).innerHTML = results;

Everything else (e.g., CSS-styling) is merely inherited from the parent webpage.
[edit]
Executing Javascript

Since the browser won't execute <script> tags when changing innerHTML, you may want to apply the following function call on document.getElementById(target):
var bSaf = (navigator.userAgent.indexOf('Safari') != -1);
var bOpera = (navigator.userAgent.indexOf('Opera') != -1);
var bMoz = (navigator.appName == 'Netscape');
function execJS(node) {
var st = node.getElementsByTagName('SCRIPT');
var strExec;
for(var i=0;i<st.length; i++) {
if (bSaf) {
strExec = st[i].innerHTML;
}
else if (bOpera) {
strExec = st[i].text;
}
else if (bMoz) {
strExec = st[i].textContent;
}
else {
strExec = st[i].text;
}
try {
eval(strExec.split("<!--").join("").split("-->").join(""));
} catch(e) {
alert(e);
}
}
}
[edit]
JavaScript Notes:
IE always returns tags in UPPER CASE, so you must search for SCRIPT and not script. Keep your SCRIPT tags in upper case for Firefox compatibility.
Do not use // comments, use /* */ instead. The eval executes all your javascript as though it was on one line, so you must end each statement with a semicolon (;).
Any functions declared in your JavaScript will go out of scope once the eval statement completes. It is possible to keep them in scope by attaching them as a method to a function that was defined at the document level.