I’ve been trying to get a slider bar working recently as part of a facebook application. To get the example on the Facebook wiki working out-of-the-box was no problem.

The problems came when I wanted to create the slider bar as the result of a user clicking on an input. For some reason, Facebook only loads 3rd party Javascript (ie. mine) in the body of the page. If a user clicks a link that calls a Javascript function before the page has finished loading, the function may fail if it depends on functions kept in external Javascript files (that have not yet loaded). 

Because of the complexity of Facebook pages, there is often between 1 and 5 seconds when a user may click one of my links even though the page hasn’t technically finished loading. If this happens, the user will either see a very cryptic error or nothing will happen. It’s a completely unacceptable user experience so I was forced to come up with the workaround below.  

var sliderCreated = false; // can only create one slider per-page with this
function createSlider() {
    if (!sliderCreated) {
        try {
            new slider(document.getElementById('output'), document.getElementById('count_slider'), 0, 100000, 250, document.getElementById('salary_min'), , 500);
            sliderCreated = true;
        } catch (error) {
            // Errors may get thrown if the fbslider.js wasn't loaded quickly enough, so we wait a second
            setTimeout(function() { createSlider() }, 1000);
        }
    }
}

This will detect any errors thrown from the creation of the slider (which relies on an external Javascript file). If an error is found, then the attempt to create the slider will occur again after a second. This has the advantage that even if the second attempt fails (if the network is very slow), it will continue to retry with a delay between each attempt.

A variable (sliderCreated) is used to detect when the slider has been successfully created. In case the link that creates the slider is still clickable after the slider is created, this variable guards against multiple sliders being spawned on the page.

It is left as an exercise to the reader to add an upper limit to the retries if required.

Once you are registered for VAT, sending in your returns every three months can be a bit of a daunting task, especially if you’re not keeping strict electronic records on a regular basis.

I’ve blogged about various online accounting packages before, but if you want to keep track of your company’s finances, and make your VAT returns effortless, KashFlow is the way to go.

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Ning is pants. Google groups are pretty pants.

Each offer a useful set of limited features, but if you’re trying to create a dynamic community, your creativity will hit the limits of their capabilities fairly quickly.

What should a complete modern social network look like? A social network is a collection of people with something in common to bind the group together. This could be an interest, it could be their employer, etc.

But what features should the modern social network offer, and does it exist as an out-of-the-box software package or hosted solution?

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If you followed along in part 1 of this article, you will have downloaded and installed Netbeans 6 to get a complete Ruby development environment. You should also have prototyped a web design idea, added some dynamic code to it, and got cosy with Ruby by implementing a small standalone application.

In this article, we’ll learn a few more techniques to help you build the next big thing for the web.

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I own several books on Rails, all of them very well written and pleasant to read. But there’s a big difference between reading a book and knowing & learning a platform. You have to code in that platform, you have to first build something trivial, and then build at least one thing that’s non-trivial. Only then do you start to become intimately familiar with a platform’s conventions, the APIs and its general approach to problem solving.

With that in mind, I present a basic guide to how I learnt Ruby on Rails at a steady pace and without feeling overwhelmed by its enormity.

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