JavaScript

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Description

With Javascript you can add functionality to a website without the need to request information from the server. A user interaction can trigger a very quick reaction. This is useful in form validation for example. But Javascript can also be used to make so-called "asynchronous" requests to the server (AJAX). That way part of a page can be updated without a reload. Last but not least, Javascript can also be used for server-side scripting.

While most users have Javascript enabled, roughly 5% don't. To make sure that these users can view the website in a meaningful way, you should never rely on only Javascript to provide some essential functionality. Javascript should rather be used to build an enhanced user experience on top of the existing functional one. This technique is called "Progressive enhancement".

A very popular framework that provides functions working the same on every browser, as well as many nice and easy-to-use effercs, is jQuery.

While I do understand the concepts of Javascript and can use it, I have to confess to a lack of practice. When I started devouring books and tutorials about web design in 2006, the first book was Deitel and Nieto: Internet and WWW How to program which I still had from my online course at City university. There I took particular interest in the chapter on Javascript and learned to write little programmes. But soon this was to be superseded by PHP, and I am now more familiar with its syntax, functions etc. than those of JavaScript. But right now (as of August 2011), my Javascript is catching up!