var bannerPlaces = document.getElementsByClassName("nookjapan_r_comic"); for (var i = 0; i < bannerPlaces.length; i++){ bannerPlaces[i].setAttribute("id", "nookjapan_r_comic"+(i + 1)); } for (var i = 0; i < bannerPlaces.length; i++){ var lists=[ '

','

','

','

','

','

','

','

','

','

','

','

','

','

','

','

','

','

','

','

','

', ]; var randnm = Math.floor(Math.random() * lists.length); var output = lists[randnm]; document.getElementById("nookjapan_r_comic"+(i + 1)).insertAdjacentHTML('afterbegin', output); }