// JavaScript Document
function test(evt) {
var data = [
'image/top/image01_s.jpg,image/top/image01_s_on.jpg,image/top/image01.jpg',
'image/top/image02_s.jpg,image/top/image02_s_on.jpg,image/top/image02.jpg',
'image/top/image03_s.jpg,image/top/image03_s_on.jpg,image/top/image03.jpg',
'image/top/image04_s.jpg,image/top/image04_s_on.jpg,image/top/image04.jpg',
];

var t = evt.target || evt.srcElement;
if (t.nodeName != 'IMG') return;
var img = document.getElementById('navi').getElementsByTagName('DIV')[0].getElementsByTagName('IMG');
var i, idx=-1, d, main = document.getElementById('main_img');
for (i=0; i<img.length; i++) if(img[i]==t) {idx=i; break; }
if (idx > -1 && idx < data.length) {
d = data[idx].split(',');
if (evt.type=='mouseover') { 
t.src = d[1];
main.src = d[2];
main.parentNode.href = t.parentNode.href;
} else {
t.src = d[0];
}
}
}