window.onload =function(){
                // ランダムに画像を表示する
                img = new Array();
                img[0] = "http://furi.mobi/img/cat1.gif";
                img[1] = "http://furi.mobi/img/cat2.gif";
                img[2] = "http://furi.mobi/img/cat3.gif";
                n = Math.floor(Math.random()*img.length);
                var cat = document.getElementById('cat');
                var imgobj = document.createElement('img');
                imgobj.src = img[n];
                cat.appendChild(imgobj);
    }