AJAX / ASP - Simple Task But I'm stuck?

I'm trying to do a simple AJAX call to an ASP page, that resets session variables and posts a little message back on completion. I'm doing this purely to learn AJAX.

The example came from W3 Schools website but since applying it to my page, I can't seem to get it to work and it's not producing any errors, which is annoying, because I can't debug it.

This is my JS, which is called when a user hits a button [Clear Form]:

function resetSearchForm()
{
var xmlhttp;
if (win开发者_JAVA技巧dow.XMLHttpRequest)
{
xmlhttp=new XMLHttpRequest();
}
else
{
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("notification").innerHTML=xmlhttp.responseText;
document.getElementById('notification').style.visibility = 'visible';
}
}
xmlhttp.open("GET","clearSearchData.asp",true);
xmlhttp.send();

document.searchFrm.searchStr.value='';
document.searchFrm.vertical.checked = true;
document.searchFrm.horizontal.checked = true;
document.getElementById('dateRange').selectedIndex = 0;
document.searchFrm.searchStr.focus();
}

And this is the ASP (clearSearchData.asp) that clears my session variables and writes a message:

Response.Expires = -1
Session("search-str-boolean") = ""
Session("search-str-plain") = ""
Session("date-range") = ""
Session("date-from") = ""
Session("date-to") = ""
Session("specificDate") = ""
Session("peopleStr") = ""
Session("orientation") = ""

Response.Write "Form has been reset"

Can anybody see where I'm going wrong? I have been looking at it for a long time and I just can't see it.

The function itself works because the last part of the function gets processed, the bit that clears the form values... but... the AJAX call doesn't happen because the session variables still contain data and the message doesn't appear.

Many thanks in advance...

UPDATE - - - - - - - - - - -

It now works. The problem was I didn't include the full URL to the ASP page. Thanks for 'thedaian' (below) for pointing that out

Chances are, something is wrong with the page you're trying to get via AJAX. Check what xmlhttp.status is, if it's 404, then you're never going to get to the point where you're printing the AJAX response. Make sure that "clearSearchData.asp" is accessible from the same directory as your javascript. This is a common problem if you have your javascript code in a separate folder from the rest of your site. Or simply put in the full URL path for the "clearSearchData.asp" so it'll definitely work.

Something to point out, the function in xmlhttp.onreadystatechange is (usually) called after it's declared in the code. In this case, it gets called after your search form fields are cleared out and reset.

The ajax call does not automatically send along a session cookie. That means the session you're clearing is not the user's session, but just a session that's been created for that ajax call alone.