function numbersonly(e) {
    var key;
    var keychar;

    if (window.event) {
        key = window.event.keyCode;
    }else if (e) {
        key = e.which;
    }else {
        return true;
    }
    keychar = String.fromCharCode(key);

    if ((key==null) || (key==0) || (key==8) ||  (key==9) || (key==13) || (key==27) || (key==43) ){
        return true;
    }else if ((("0123456789").indexOf(keychar) > -1)) {
        return true;
    }else {
        return false;
    }
}