php - Executing javascript script after ajax-loaded a page - doesn't work

Question

I'm trying to get a page with AJAX, but when I get that page and it includes Javascript code - it doesn't execute it.

Why?

Simple code in my ajax page:

<script type="text/javascript">
alert("Hello");
</script>

...and it doesn't execute it. I'm trying to use Google Maps API and add markers with AJAX, so whenever I add one I execute a AJAX page that gets the new marker, stores it in a database and should add the marker "dynamically" to the map.

But since I can't execute a single javascript function this way, what do I do?

Is my functions that I've defined on the page beforehand protected or private?

** UPDATED WITH AJAX FUNCTION **

function ajaxExecute(id, link, query)
{
    if (query != null)
    {
        query = query.replace("amp;", "");
    }

    if (window.XMLHttpRequest)
    {
        // code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp=new XMLHttpRequest();
    }
    else
    {
        // code for IE6, IE5
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }

    xmlhttp.onreadystatechange=function()
    {
        if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
            if (id != null)
            {
                    document.getElementById(id).innerHTML=xmlhttp.responseText;
            }
        }
    }

    if (query == null)
    {
        xmlhttp.open("GET",link,true);
    }
    else
    {
        if (query.substr(0, 1) != "?")
        {
            xmlhttp.open("GET",link+"?"+query,true);
        }
        else
        {
            xmlhttp.open("GET",link+query,true);
        }
    }
    xmlhttp.send();
}

** Solution by Deukalion **

var content = xmlhttp.responseText;

if (id != null)
{

    document.getElementById(id).innerHTML=content;
    var script = content.match("<script[^>]*>[^<]*</script>");

    if (script != null)
    {
        script = script.toString().replace('<script type="text/javascript">', '');
        script = script.replace('</script>', '');
        eval(script);

    }
}

and on certain events, I had to within the script addevent listeners instead of just making a "select onchange='executeFunctionNotIncludedInAjaxFile();'" I had to addEventListener("change", functionName, false) for this. In the script that is being evaluated.

Answer 1

When you update your page by doing something like setting a container's innerHTML to some updated content, the browser simply will not run the scripts in it. You can locate the <script> tags, get their innerHTML (IE may prefer innerTEXT), and then eval() the scripts yourself (which is pretty much what jQuery does, though it finds the scripts with a regex before updating the DOM).