What is it?
Ajax is a collection of technologies and techniques intended to make web applications as responsive, interactive and rich as their desktop equivalents.
Instead of reloading the page every time a user makes a change, Ajax enables small amounts of data to be exchanged with the server asynchronously. This eliminates much of the time users spend waiting, and potentially reduces the overload that afflicts e-commerce sites at busy times.
In particular, Ajax can “break” the back button that returns the user to the unmodified page. For this reason Ajax has provoked strong opposition from web usability advocates such as Jakob Nielsen.
Where did it originate?
The term Ajax was coined in early 2005 by Jesse James Garrett in his article Ajax: A New Approach to Web Applications.
What is it for?
Ajax is used for the routine tasks that form the core of most people’s use of the internet: updating records, filling in forms, and answering search queries. Ajax reduces the requirement to fetch a full page of HTML each time a small change is made.
Garrett argued that the web was developed as hypertext medium – not for software applications – and although the pre-Ajax conventions made technical sense, they did not make for a great user experience. “Once an interface is loaded, why should the user interaction come to a halt every time the application needs something from the server?” he said.
What makes it special?
According to its proponents, Ajax not only improves responsiveness for the user, it also enables web developers to create the kind of richly-functional interfaces their desktop application colleagues take for granted. For a counter-view, see
How difficult is it to master?
Since Ajax uses technologies most web developers already work with, it should be less challenging than learning a new language. However, it uses these technologies in complex ways that contain pitfalls for the inexperienced.
Where is it used?
The most high-profile user is Google, with Gmail, Google Maps and other applications.
What is coming up?
Ajax is set to become part of most integrated development environments and frameworks, including Microsoft’s Atlas, IBM’s Websphere Studio, the open source Eclipse, and Ruby on Rails.
There are many commercial and community Ajax sites offering training material. Adaptivepath.com, IBM’s Developerworks site and the O’Reilly network have plenty of Ajax resources.
Rates of pay
Ajax is increasingly a requirement in adverts for web developers, particularly senior posts. Average salaries for web developers range from £30,000 to £38,000.