function check_status() {
    var rate = document.getElementById("option_var_ids");
    var copy = document.getElementById("qty");

    if (rate && copy) {
        if (rate.value == "" || rate.value == 0)
        {
            copy.className = "disabledbutton";
            copy.disabled = "disabled";
        }
        else {
            copy.disabled = '';
        }
    }
}

function checknumber() {
    var qtys = document.getElementById("qty");
    var mybutton = document.getElementById("cart_button");

    if (qtys && mybutton) {
        if (qtys.value == "" || qtys.value == 0)
        {
            mybutton.className = "disabledbutton";
            mybutton.disabled = "disabled";
        }
        else {
            mybutton.disabled = '';
        }
    }
}