function yearSelected() {
    var elem = document.getElementById('sel_year');
    if (!elem) {
        return false;
    }
    var selYear = elem.options[elem.selectedIndex].value;
    if (selYear) {
        /* year is selected */
        var addr = window.location.href;
        if (addr.indexOf('?') != -1) {
            addr = addr.substr(0, addr.indexOf('?'));
        }
        addr += '?ry=' + selYear;
        window.open(addr, '_self');
    }
}

function monthSelected() {
    var elem = document.getElementById('sel_year');
    if (!elem) {
        return false;
    }
    var selYear = elem.options[elem.selectedIndex].value;
    var elem = document.getElementById('sel_month');
    if (!elem) {
        return false;
    }
    var selMonth = elem.options[elem.selectedIndex].value;
    if (selYear && selMonth) {
        /* both year and month are selected */
        window.open('cuts_of_the_week.php?m=' + selYear + '-' + selMonth, '_self');
    }
}