Javascript herschrijven voor nieuwere browsers

function showMenu(key,sender)
{
    hideSelects(true);
    for (var i=0; i < 15; i++)
    {
        var sm = document.getElementById('sm_'+i);

        if (sm != null)
        {
            sm.style.display = 'none';
            var t=0;
            var div = document.getElementById('menuContainer');
            tr = div.childNodes[0].childNodes[0].childNodes[0];
            td = tr.childNodes[key];

            img = document.getElementById('mi_'+key);
            if(sender.className.indexOf('Over') > 0 )
            {
                img.src='http://basis/images/sortupover.gif';
            }
            else
            {
                img.src='http://basis/images/sortup.gif';
            }

        }
    }

    stopTimer();
    var submenu = document.getElementById('sm_'+key);
    submenu.style.display = '';
    submenu.style.left = td.offsetLeft;
    if (submenu.clientWidth < td.offsetWidth)
    {
        submenu.style.width = td.offsetWidth + 'px';
        submenu.childNodes[0].style.width = td.offsetWidth + 'px';
    }
    submenu.style.display = 'inline';
}