prova questo esempio

codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="it" xml:lang="it">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
        <script type="text/javascript">
        // <![CDATA[
        
        function writeTime() {
            f_ore = document.getElementById('ore');
            f_min = document.getElementById('minuti');
            dt = new Date();
            f_ore.value = (dt.getHours() < 10)? "0" + dt.getHours() : dt.getHours();
            f_min.value = (dt.getMinutes() < 10)? "0" + dt.getMinutes() : dt.getMinutes();
        }
        
       function changeTime(f, val) {
            f_val = parseInt(document.getElementById(f).value, 10);
            f_val += val;
            
            if ((f_val < 0) && (f == 'ore')) f_val = 23;
            if ((f_val > 23) && (f == 'ore')) f_val = 0;
            
            if ((f_val < 0) && (f == 'minuti')) f_val = 59;
            if ((f_val > 59) && (f == 'minuti')) f_val = 0;
            
            document.getElementById(f).value = (f_val < 10)? "0" + f_val : f_val;

       }
        
        window.onload = writeTime;
        // ]]>
        </script>
        
        <style type="text/css">
            div {
                float       : left;
                width       : 60px;
            }
            
            input {
                height      : auto;
                width       : 54px;
                font-size   : 40px;
            }
            
            button {
                width       : 10px;
                text-align  : center;
            }
        </style>
    </head>

<body>

    <div>
        <input type="text" readonly="readonly" id="ore" />

        <button onclick="changeTime('ore' , -1);">&lt;</button><button onclick="changeTime('ore' , 1);">&gt;</button>
    </div>

    <div>
        <input type="text" readonly="readonly" id="minuti" />
        <button onclick="changeTime('minuti' , -1);">&lt;</button><button onclick="changeTime('minuti' , 1);">&gt;</button>
    </div>

</body>
</html>

Ciauz

Edit: vedo adesso la provenienza: stasera vado al bowling di quarto d'altino...