Hot skills : Rise of Ajax drives demand for Javascript developers

Scripting language enables rich internet applications

What is it?

Javascript is a popular scripting language most commonly used for web development.

The original intention behind Javascript was to produce a Java-like scripting language that would be easier to use. The syntax is similar to Java, and to Java's precursor C++.

Javascript is a superset of the Ecmascript language, a standard maintained by the European Computer Manufacturers Association (Ecma). After Javascript was released by Sun and Netscape, Microsoft released its own version, JScript, and it was JScript that was submitted to Ecma as the basis of the standard. Adobe Flash's Actionscript is another Ecmascript-compatible language.

Javascript demand is high thanks to the spread of Ajax (Asynchronous Javascript and XML), and it has long been the most widely used scripting language.

It is also first choice for malware writers, with obfuscated Javascript the second most prevalent malware type in Sophos's monthly list of top malware threats.

Where did it originate?

Javascript was developed by Brendan Eich at Netscape, first under the name Mocha, and then more formally as Livescript - the name it would probably have kept if it had not been for Netscape's agreement with Sun. Javascript was first deployed in the Netscape Navigator browser in 1995.

What's it for?

Javascript is most commonly used for client-side scripting applications that are embedded in HTML pages to enable the pages to be more responsive to the user than a server-based function would be.

This is the basis of the Ajax approach: instead of reloading the whole page every time the user makes a change or request, the application exchanges the minimum possible data with the server, and the application remains available to the user.

As a result, Ajax applications can have the kind of rich user interfaces usually only available with desktop applications. For the same reasons, Javascript is often chosen for large parts of web-based applications, such as Gmail. Javascript is also widely found in web server side applications.

Javascript supports prototyping as well as procedural and object-oriented programming. Developers need to consider that, on the client side, Javascript applications are likely to encounter an extremely wide range of environments, browsers and browser versions. Javascript is interpreted differently by the various browser suppliers.

What makes it special?

Because of the uncertainties of the client-side environment and the just-get-by nature of much programming, Javascript has a poor reputation. There is a move to change this through something called Unobtrusive Javascript, which separates Javascript functionality from a web page's content and defines best practice to avoid problems such as browser inconsistencies.

As a result of this - and with Ajax in mind - Javascript is being considered for more substantial applications than form validation and altering images in response to mouse movements.

How difficult is it to master?

Javascript was designed to be learned quickly by people with C++ and Java backgrounds.

What systems does it run on?

Most browsers, and tools such as Adobe's Flash, Acrobat and Dreamweaver.

More hot skills


Classroom-based Javascript training is available, and there are plenty of good, free internet tutorials. Javascript creator Brendan Eich has posted material in various places online and has co-written a book on the subject, The Javascript Bible.




rates of pay

Javascript developers earn between £20,000 and £35,000, depending on seniority and skills, and potentially much more with Ajax experience. Computer Weekly/SSL salary survey


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