var id = 10; // Total number of images
var ranimage = new Array(id); // Array to hold the filenames

ranimage[0] = "images/01.jpg";
ranimage[1] = "images/02.jpg";
ranimage[2] = "images/03.jpg";
ranimage[3] = "images/04.jpg";
ranimage[4] = "images/05.jpg";
ranimage[5] = "images/06.jpg";
ranimage[6] = "images/07.jpg";
ranimage[7] = "images/08.jpg";
ranimage[8] = "images/09.jpg";
ranimage[9] = "images/10.jpg";

function choseRandom(range) {
if (Math.random)
return Math.round(Math.random() * (range-1));
else {
var now = new Date();
return (now.getTime() / 1000) % range;
}
}
//
var choice = choseRandom(id);