function keypress(e) {
    var key, keychar;
    key = getKey(e);
    if(key==null) return true;
    keychar = String.fromCharCode(key);
    if('1234567890'.indexOf(keychar) != -1) return true;
    else if(key==null || key==0 || key==8 || key==9 || key==13 || key==27) return true;
    else return false; }

function getKey(e) {
    if(window.event) return window.event.keyCode;
    else if(e) return e.which;
    else return null; }