Display content using variables stored in data attributes

gistfile1.js

var $footer = $('#footer'),
    $themeURL = $footer.data('theme'),  
    $currentPage = $footer.data('page');

window.onload = function () {
    var display = $('#scene').css('display');
    if (display == 'block') {       
        displayFeatures();
    }
}(this);


function getHTTPObject() {
    var xhr = new XMLHttpRequest();
    return xhr;
}

function displayFeatures() {
    var request = getHTTPObject();
        if (request) {
            request.onreadystatechange = function() {
                displayResponse(request);
            };      
            request.open("GET",$themeURL+"scene-images.php?page="+$currentPage, true);
            request.send(null);                             
        }
}

function displayResponse(request) {
    if (request.readyState == 4) {
        if (request.status == 200 || request.status == 304) {
            var container = document.getElementById("scene-container");
            container.innerHTML = request.responseText;        
        }
    }
}