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Welcome to Geoff Hayward's Weblog

Commenting on Java, JavaFX, Java EE, Joomla, and IoT.

All the versions of Joomla I know have shipped with the GeSHi syntax highlighter. The GeSHi Syntax highlighter comes in the form of a plugin that is by default unpublished. Its power comes from the fact that it does all the syntax highlighting server side. Meaning caching can be taken full advantage of.

The GeSHi - Generic Syntax Highlighter is an award-winning piece of software released under the GNU GPL license and is packaged into a plugin by Joomla ready to be used by any author or publisher who needs to highlight the syntax of their examples.

When I found the Joomla GeSHi plugin, I discovered there was very little documentation on how to use the Joomla plugin. This may have been because it is quite easy to uses once you know how, however, I didn't know how at the time. I had to piece together very small snippets of information until the 'how to' for me came together.

Here is How to Use the Joomla GeSHi Plugin

The first step is to go to Joomla's plugin manager. Search for 'GeSHi' and publish the result. The Joomla GeSHi plugin will then be active ready for the Joomla's advanced event system (sometimes referred to as hooks in other CMS's terminology) to call it during 'onContentPrepare'.

Now when adding content simply use the HTML pre tag with the GeSHi xml:lang attribute. The value of the attribute needs to be the language that is to be syntax highlighted. For example:

<script type="text/javascrpt">
	/* Highlighted JavaScript stuff  */

will give you a syntax highlighted JavaScript snippet.

TinyMCE Gets in the Way of the Joomla GeSHi Plugin

Be warned TinyMCE is a bit of a pain when it comes to using the GeSHi plugin. The best solution is to just disable TinyMCE. What about the non-technical users? - you may ask. Well you can disable TinyMCE for your account only or the user group of authors who need syntax highlighting - for example you could set up a 'Technical Author' group. Another alternative I have found is to use the JCE editor. When the JCE editor is configured properly, it will play nicely with the GeSHi Joomla plugin.

What Languages Will the Joomla GeSHi Plugin Highlight?

Version 3 of Joomla will get GeSHi to highlight following:

  • CSS
  • Diff (Diff File Format)
  • HTML
  • ini (Configuration files)
  • JavaScript
  • MySQL
  • PHP
  • SQL
  • XML

They are All Triggered Respectively as Follows:

<pre xml:lang="CSS">
<pre xml:lang="Diff">
<pre xml:lang="HTML">
<pre xml:lang="INI">
<pre xml:lang="Javascript">
<pre xml:lang="MySQL">
<pre xml:lang="PHP">
<pre xml:lang="SQL">
<pre xml:lang="XML">


The Joomla GeSHi Plugin is a great tool for authors and publishers were syntax highlighting is in need. The Joomla GeSHi Plugin is not difficult to use as this article tries to show and help with. Out-of-the-box the Joomla GeSHi Plugin has a good selection of languages that technical bloggers and writers are likely to need. If the language you need is not included, please see below for: What if the language I need is not included? Otherwise I hope this article was helpful.

What if the Language I Need is Not Included?

Well you could just add it to the GeSHi folder within the plugin - that is how GeSHi itself works. However, as I am sure you know, this is hacking the Joomla core and is bad and unnecessary. The solution is to copy the Joomla GeSHi plugin folder to your local machine. Then add whichever languages you need that are available from the GeSHi project to the plugin's GeSHi folder. Then repackage it up with an amended install XML file, zip it, and install it back into Joomla. Do not forget to publish your extended version and you're away.

Here is one I prepared earlier that has all the languages GeSHi has available:


  • For performance reasons I recommend removing the languages you will not be using
  • It comes with no warranty

Tags: GeSHiJoomla


At the time of writing this article I have not seen websites with completely successful attempts at loading icons which appear when html anchor tags are clicked. I therefore decided to find my own solution.

By completely successful I mean the website continues to function as if the icons where not there at all. For example pressing 'Ctrl' and left clicking the link of an anchor tag a new tab should appear within the user's browser. The original tab from which the click was initiated should remain the same.

At no time should the loading icons prevent the default behaviour of the browser. Not when it is a link away from the page either internally or externally relative to the website. The reason being: You do not want to upset search engine spiders, accessibility etc.. Remember we are trying to enhance the website's usability without taking anything away.

The CSS Problem with Anchor Tags Loading Icons

The main problem I had to overcome first was: Browsers, with the exception of Firefox, just do not request images from the server once a page has received an anchor click that goes to a new page. So how do we solve a problem like this? The solution is to already have the requested loading icon image before the anchor tag is clicked.

So now the question becomes: Where to hide the loading icon ready for the click of the anchor tag? I admit I got very inventive whilst experimenting with this problem. However, the solution I found and settled on was simple. That is to simply hide the loading icon on the anchor itself. In other words the icon is always there with a negative 100% on the x-axes. Then all that needs to be done is shift the position of the loading icon image into view once you need it. So now the CSS class called 'loading' is put into the stylesheet ready for action.

.menu a {
    background: url("../images/loading.gif") no-repeat scroll -100% 50% transparent;
.menu a.loading {
    background-position: 100% 50%;

Solved! Or is it? That at least solves the CSS part of the loading icons on the anchor tag problem.

JavaScript for Anchor Tags Loading Icons

Now all we need to do is to shift the x-axes of the loading icon image by adding the class named 'loading' to the anchor when clicked. This of course, is easier said than done.

Sticking to the discipline that HTML provides structure, CSS provides presentation and JavaScript provides behaviour all the JavaScript in the solution I found loads from a JS file.

The first thing the solution needs to do is to wait for the DOM to be loaded. It then needs to find all the anchor tags that are going to have loading icons. Once it has found the anchor tags, it needs to add a click event. As this is pretty standard functionality given by JavaScript abstraction layers, I made my life easier by using Mootools. However, there is nothing library specific in the solution that I am giving here. Prototype JS, jQuery, etc. will work just fine.

So the click event! This is the tricky part that can stop the user's browser working as it should. When the anchor is clicked, we add the class named 'loading' to the anchor tag. However, the 'Ctrl' click, 'Alt' click and 'shift' click need to not have an effect when the event is fired. So an if not statement needs to wrap around the event to stop the class 'loading' being added.

For example:

if(!event.control && !event.alt && !event.shift){

That is all there is to it! It was easy once I solved it.


For those of you that do not know the JSON format; JSON stands for JavaScript Object Notation and is a very powerful and fast way of getting and using data. It is fast because the client does not need to parse it unlike XML. At your keyboarding finger tips you have a JavaScript collection ready to roll. But the best part of it is it circumvents the cross domain malarkey. That's right no proxy needed.

So let me give you a demo using a well-known website that lets you feed on their data. Of course this demo is only a demo and I would not use script tags in the body of the document if it was a live website.

<div id="twitter"><!-- a Handle --></div>
// This function must be known before the call
function getTweets(data)
    var html = '';
    for (var i = 0; i < data.length; i++){
        html += '<p>' + data[i].text + '</p>';
    document.getElementById('twitter').innerHTML = html;
<script type="text/javascript" src="" ></script>

The example I created about will right out the main text from all of your tweets paragraph by paragraph thus demonstrating the elegance of JSON. Try it yourself but, remember to check the API of the data feed you are getting JSON from to see what tasty nibbles are in store.


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With the ResponsiveMedia plugin for Joomla it is easy to add 3rd party content from YouTube, Vimeo, and Instagram right in to any Joomla! article.