web design

After searching  for a simple jquery image gallery for an online store I decided to make my own. There were several solutions that were close to what I wanted, but quite there. The project required an simple large vierw of an image with multiple thumbnails below, when hovered upon switched the large image. The requirements were as follows: cross browser compatible (IE6 plus, Chrome and Firefox – all the major browsers), have a nice fading effect between image changes and be totally degradable if JavaScript was turned off.

First of all, take a peek and the finished JQuery image gallery – I’ve put the gallery in context on a product detail page for an ecommerce store.

JavaScript and JQuery to the Rescue!

JQuery was the JavaScript framework of choice and made it easy to get things up and running. Techniqually the same effect can be achieved without JQuery, but for simplicity I’m using JQuery. The code is quite easy to follow and I’ll just pickup  up on the main parts.

Firstly we’ll start off with the HTML – simply two dividers, with an unordered lists for the thumbnail images:

<div id="bigpic" class="b"><img src="images/big/iphone-3-big.jpg" alt="iPod Shuffle 16GB Zoom View" />
<p id="desc">iPod Shuffle 16GB Zoom View</p>

</div>

<div id="thumbs">
<ul>
	<li><a rel="images/small/iphone-1-small.jpg" href="images/big/iphone-1-big.jpg">
<img src="images/small/iphone-1-small.jpg" alt="iPod Shuffle Front View In Blue!" />
</a></li>
	<li> <a rel="images/small/iphone-2-small.jpg" href="images/big/iphone-2-big.jpg">
<img src="images/small/iphone-2-small.jpg" alt="iPod Shuffle Dual View Grey!" />
</a></li>
	<li> <a rel="images/small/iphone-3-small.jpg" href="images/big/iphone-3-big.jpg">
<img src="images/small/iphone-3-small.jpg" alt="iPod Shuffle 16GB Zoom View" />
</a></li>
</ul>
</div>

The main image is housed in the divider with the id of ‘bigpic’. I’ve also added a description below the big image – this will change when the image is hovered over to the thumbnail alternate text. Each thumbnail link goes directly to the enlarged version of the image – this way, the gallery will still work when JavaScript is turned off.

The JQuery Magic ….

Right after including the JQuery library (I recommend you make use of Google CDN for this – there are many reasons to let Google host your JQuery files) I have included an int,js file – this contains all the gallery JavaScript. The int file is a small file that catches a hover on each thumbnail and switches the main gallery image (Our ‘bigpic’ divider). All the code is contained within the mahic document.ready listener. The first half of the file catches the hover on a thumbnail:

$('#thumbs ul li a').hover(
		function() {
			var currentBigImage = $('#bigpic img').attr('src');
			var newBigImage = $(this).attr('href');
			var currentThumbSrc = $(this).attr('rel');
			switchImage(newBigImage, currentBigImage, currentThumbSrc);
		},
		function() {}
	);

Here we are getting the currentBig image href, the new big image (from our thumbs href) and current thumbnail src. The second empty fucntion is included to say ‘don’t do anything when hovering away’. Exclude this empty function and the hover event will continue to fire when you leave the image. Now we have these three variables we pass them to our switchImage function, code below:

function switchImage(imageHref, currentBigImage, currentThumbSrc) {

		var theBigImage = $('#bigpic img');

		if (imageHref != currentBigImage) {

			theBigImage.fadeOut(250, function(){
				theBigImage.attr('src', imageHref).fadeIn(250);

				var newImageDesc = $("#thumbs ul li a img[src='"+currentThumbSrc+"']").attr('alt');
				$('p#desc').empty().html(newImageDesc);
			});

		}

	}

This is quite self explanatory. The first check made is that the current big image is not the same as the target big image – if this was true we would fade in and out the same image, which leads to a rather weird looking effect. If both paths match, the user has hovered over the thumbnail of the current big image (in this case nothing would happen). Hovering over any other image will result in the current big image fading out, setting the big image src to the src from the thumbnail (the new image) and populating our description paragraph.

Using the Gallery in a Production Website

In the example 3 static large and small images have been manually added for simplicity. In a real website, maybe an online store, you would retrieve this information from a database. Another thing to note is image sizes. I always find it useful to let users upload whatever file resolution they want, giving them the exact pixels as a recomendation. To ensure that a particularly large file wouldn’t break the layout I tend to sue image resizing scripts, such as the excellent smart image resizer from shifting pixel – uploaded images can be automatically scaled to dimensions of your choosing.

Also, at some point I’ll learn about making your owns plugins for JQuery and turn this into a self contained plugin

There’s not a lot more to this to be honest. tested in IE6, IE7, IE8, Chrome and Firefox – all working nicely.

Take a look at the final result or download the source files. Enjoy!