// Randomly choose an image to display from the given list (see imageList).
//
// Requires VA.util.getCookie() and VA.util.setCookie() from cookies.js
//
//
// Place this code in the where you want the image to appear.
//
var VA;
if (!VA) VA = {};
if (!VA.widget) VA.widget = {};
// imageList - A list of images to choose from. Filename and extension only (no path).
// baseDirectory - The relative path to the image files (don't forget the trailing slash!)
// NOTE: all images must be in the same directory
VA.widget.RandomImage = function(imageList, baseDirectory) {
this.imageList = imageList;
this.baseDirectory = baseDirectory ? baseDirectory: '';
// Preload all images
for (var i = 0; i < imageList.length; i++) {
var newImage = new Image();
newImage.src = baseDirectory + imageList[i];
}
// Don't repeat images across successive page loads by placing the index
// of the random image in a cookie
var randomIndex = Math.floor(Math.random() * imageList.length);
if (typeof document.cookie != 'undefined'){
var lastIndex = VA.util.getCookie('lastImageIndex');
do{
if (lastIndex)
randomIndex = Math.floor((Math.random() * imageList.length));
else
break;
} while (lastIndex == randomIndex);
VA.util.setCookie('lastImageIndex', randomIndex, 0); // remember for next time
}
// This is dangerous if the image isn't found, but it's necessary because it will be placed later in the page
// if we wait for the image to finish loading - which is also bad. As long as the image loads, everything's fine.
document.write('
');
}
if (!VA.util) VA.util = {};
// http://www.quirksmode.org/js/cookies.html
VA.util.setCookie = function(name,value,days) {
if (days) {
var date = new Date();
date.setTime(date.getTime()+(days*24*60*60*1000));
var expires = "; expires="+date.toGMTString();
}
else var expires = "";
document.cookie = name+"="+value+expires+"; path=/";
}
// http://www.quirksmode.org/js/cookies.html
VA.util.getCookie = function(name) {
var nameEQ = name + "=";
var ca = document.cookie.split(';');
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
VA.widget.RandomImage([
'banner1.jpg',
'banner2.jpg',
'banner3.jpg',
'banner4.jpg'
], '../images/');