/* Rollover Buttons Functions */
function rollImage(src,id){
    document.getElementById(id).src = document.getElementById(id).src.replace('btn.png','btn_rollover.png');
}
    
function unrollImage(src,id){
    document.getElementById(id).src = document.getElementById(id).src.replace('btn_rollover.png','btn.png');
}

// Quick Script to change background image
function changeBG() {
    var randomnumber = Math.floor(Math.random() * 3) + 1;
    if (querySt('pic') != "") { randomnumber = querySt('pic') };
    document.getElementById('topBox').style.backgroundImage = "url('http://www.ed-coll.ac.uk/images/banners/home" + randomnumber + ".jpg')";
}

//Retrieve URL Query String
function querySt(ji) {
    hu = window.location.search.substring(1);
    gy = hu.split("&");
    for (i = 0; i < gy.length; i++) {
        ft = gy[i].split("=");
        if (ft[0] == ji) {
            return ft[1];
        }
    }
    return "";
}