//imagerandom.js

var txt = new Array();
txt[0]="top_img01.jpg";
txt[1]="top_img02.jpg";
txt[2]="top_img03.jpg";
txt[3]="top_img04.jpg";
txt[4]="top_img05.jpg";

mmax = 5;
txtno = Math.floor(Math.random() * mmax);
document.write("<img src='"+txt[txtno]+"'>");