Saturday, 13 September 2008

JavaScript image changer

I'm definitely not a JavaScript programmer. I just wanted to have a simple script that would change background image on the site automatically in a loop. I couldn't find a ready ouf-of-the-box solution so I've created my own. It's based on YUI. The only reason of choosing YUI over Prototype or JQuery was that YUI it's used by LightFlow. The target site of my image loop changer was already using LightFlow so JavaScript could be shared.

Here is my code. This code is definitely not mature but still maybe you'll find it helpful. The following things should be applied to your HTML:

1. Load the YUI library
<script type="text/javascript"

2. Create a DIV with the original image background (the one loaded initially)
<div id="imageLoopDiv" style="background: url(img1.jpg) no-repeat;">

3. Initialize JavaScript: provide the list of images (loopImages), pre-load the images so that they don't blink when changed, and register the function that automatically switches backgrounds
<script type="text/javascript">

var loopImages=new Array('img1.jpg','img2.jpg','img3.jpg');

var showNextImage=function(){
var currentImage=YAHOO.util.Dom.getStyle('imageLoopDiv','background');
var currentIdx=0;
for(var i=0;i<loopImages.length;i++)
if(currentImage.indexOf(loopImages[i])!=-1){currentIdx=i; break;}
var newImage=loopImages[(currentIdx+1)%loopImages.length];
YAHOO.util.Dom.setStyle('imageLoopDiv','background','url('+newImage+') no-repeat');

for(var i=0;i<loopImages.length;i++){
var img=new Image(); img.src='../img/'+loopImages[i];


The running example of this scipt is This scripts are script.js and yui-utilities.js.

Sunday, 7 September 2008

Java links

This is a list of Java related links I've gathered over time.

2007-12-22: A introduction to REST

2007-12-05: Web framework comparison again. Matt Raible: first PDF (classic Java frameworks) and the the second PDF (not so pure Java).

2007-12-05: J2EE news. I used to read TheServerSide but recently InfoQ seems be much more interesting.

2007-11-10: SOFEA - the future(?) of web frameworks. By reading this discussion (actual paper - pdf) you'll learn what the web framework should be and why Java web frameworks are anti-frameworks.

2007-07-19: catch (InterruptedException e). Did you ever have a problem what to do with InterruptedException? Here is a tip.

2007-01-05: Design Driven Development. A book good book about architecture and design, without any technology dependencies at InfoQ

2006-02-17: AOP Article. A good article on AOP – at developerWorks (not only on AOP: design patterns, frameworks, QA, etc. also addressed). Before this I was rather skeptic about AOP. Now I’m rather excited J - I’d like to see a really OO system, with design patterns, and some crosscutting concerns designed as Aspects.

2005-04-25: Annotation. When to annotate - read a Bill Burke blog entry

Web Frameworks. See comparison by Matt Raible [PDF]

Micro Benchmarks. On testing small aspects of the application - at developerWorks

Exceptions. J2EE Exception handling strategy - a JavaWorld article