// 読み込みファイル //
var menuimage = new Array();
for(i=0; i<14; i++){
    menuimage[i] = new Image();
}
menuimage[0].src = "images/navi_01.jpg";
menuimage[1].src = "images/navi_01_on.jpg";
menuimage[2].src = "images/navi_02.jpg";
menuimage[3].src = "images/navi_02_on.jpg";
menuimage[4].src = "images/navi_03.jpg";
menuimage[5].src = "images/navi_03_on.jpg";
menuimage[6].src = "images/navi_04.jpg";
menuimage[7].src = "images/navi_04_on.jpg";
menuimage[8].src = "images/navi_05.jpg";
menuimage[9].src = "images/navi_05_on.jpg";
menuimage[10].src = "images/navi_06.jpg";
menuimage[11].src = "images/navi_06_on.jpg";
// イメージ変更 //
function alternate(name,num){
    document.images[name].src = menuimage[num].src;
}