js 顯示網頁時間

function startTime()
    {
        var today=new Date()
        var y=today.getFullYear();
        var mon=today.getMonth();
        var day=today.getDay();
        var h=today.getHours();
        var m=today.getMinutes();
        var s=today.getSeconds();
// add a zero in front of numbers<10
        m=checkTime(m);
        s=checkTime(s);
        document.getElementById('time_show').innerHTML=y+'-'+(mon+1)+'-'+(day+1)+' '+h+":"+m+":"+s;
        t=setTimeout(function(){startTime()},500);
    }

    function checkTime(i)
    {
        if (i<10)
        {
            i="0" + i;
        }
        return i;
    }