var randnum = Math.random();
var inum = 6;// Change this number to the number of images you are using.
var rand1 = Math.round(randnum * (inum-1)) + 1;
images = new Array
images[1] = "../../assets/images/banners/banner1.jpg"
images[2] = "../../assets/images/banners/banner2.jpg"
images[3] = "../../assets/images/banners/banner3.jpg"
images[4] = "../../assets/images/banners/banner4.jpg"
images[5] = "../../assets/images/banners/banner5.jpg"
images[6] = "../../assets/images/banners/banner6.jpg"

// Ensure you have an array item for every image you are using.
var image = images[rand1]