Accessing XML on page load with Jquery

Question

I am trying to access a file called "slider1.xml" and access information to post onto my web page. I am using Jquery, and right now I can't seem to get it to work. I think the issue may be with how I am calling the function.

slider1.xml:

<?xml version="1.0" encoding="UTF-8"?>
<note1>Here is a note</note1>

main.js:

$(document).ready(function() {
    function loadXMLDoc(url){
        var xmlhttp;
        var txt, x, xx, i;
        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) {
                x = xmlhttp.responseXML.documentElement.getElementsByTagName("note1").nodeValue;
                alert(x);
            }
        }
        xmlhttp.open("GET", url, true);
        xmlhttp.send();
    }

    loadXMLDoc("slider1.xml"); // this line is causing an error
});