When you do an AJAX call you just grab the content from that page. JavaScript treats it as a string (not code). You would have to add the content from the page to your DOM in your AJAX callback.
$.get('/alertscript.php', {}, function(results){
$("html").append(results);
});
Make sure you change the code to fit your needs. I'm supposing you use jQuery...
Edited version
load('/alertscript.php', function(xhr) {
var result = xhr.responseText;
// Execute the code
eval( result );
});
function load(url, callback) {
var xhr;
if(typeof XMLHttpRequest !== 'undefined') xhr = new XMLHttpRequest();
else {
var versions = ["MSXML2.XmlHttp.5.0",
"MSXML2.XmlHttp.4.0",
"MSXML2.XmlHttp.3.0",
"MSXML2.XmlHttp.2.0",
"Microsoft.XmlHttp"]
for(var i = 0, len = versions.length; i < len; i++) {
try {
xhr = new ActiveXObject(versions[i]);
break;
}
catch(e){}
} // end for
}
xhr.onreadystatechange = ensureReadiness;
function ensureReadiness() {
if(xhr.readyState < 4) {
return;
}
if(xhr.status !== 200) {
return;
}
// all is well
if(xhr.readyState === 4) {
callback(xhr);
}
}
xhr.open('GET', url, true);
xhr.send('');
}