if(document.images) {
 var imgs = new Array();
 imgs[0] = new Image();  imgs[0].src = "imge/bt_top/1.jpg"; //画像パスを入力
 imgs[1] = new Image();  imgs[1].src = "imge/bt_top/2.jpg";
 imgs[2] = new Image();  imgs[2].src = "imge/bt_top/3b.jpg";
 imgs[3] = new Image();  imgs[3].src = "imge/bt_top/4b.jpg";
 imgs[4] = new Image();  imgs[4].src = "imge/bt_top/5.jpg";
 imgs[5] = new Image();  imgs[5].src = "imge/bt_top/6.jpg";
 imgs[6] = new Image();  imgs[6].src = "imge/bt_top/7.jpg";
 imgs[7] = new Image();  imgs[7].src = "imge/bt_top/8.jpg";
 imgs[8] = new Image();  imgs[8].src = "imge/bt_top/9c.jpg";
 imgs[9] = new Image();  imgs[9].src = "imge/bt_top/10c.jpg";
 imgs[10] = new Image();  imgs[10].src = "fbposta/fbposta1.gif";
 imgs[11] = new Image();  imgs[11].src = "fbposta/fbposta2.gif";
 }

function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}