var imagenumber = 14 ; 

var randomnumber = Math.random() ; 

var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ; 

images = new Array 

images[1] = "images/banner01.jpg" 
images[2] = "images/banner02.jpg" 
images[3] = "images/banner03.jpg" 
images[4] = "images/banner04.jpg" 
images[5] = "images/banner05.jpg" 
images[6] = "images/banner06.jpg" 
images[7] = "images/banner07.jpg" 
images[8] = "images/banner08.jpg" 
images[9] = "images/banner09.jpg" 
images[10] = "images/banner10.jpg" 
images[11] = "images/banner11.jpg" 
images[12] = "images/banner12.jpg" 
images[13] = "images/banner13.jpg" 
images[14] = "images/banner14.jpg" 
var image = images[rand1]