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

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