$(document).ready(function() { var randomImages = ['bimg_1','bimg_2','bimg_3','bimg_4','bimg_5','bimg_6','bimg_7','bimg_8','bimg_9','bimg_10','bimg_11','bimg_12','bimg_13','bimg_14','bimg_15','bimg_16','bimg_17','bimg_18','bimg_19','bimg_20','bimg_21','bimg_22']; var rndNum = Math.floor(Math.random() * randomImages.length); $("div#ranbanner").css({ background: "url(banners/" + randomImages[rndNum] + ".png) no-repeat" }); });