Bring your Web pages to life with Javascript

What is Javascript?

Javascript is the most widely used Web scripting language, ahead of Microsoft's VBScript, which, together with JScript, forms Microsoft Windows Script. Scripting languages are used to create executable content in Web pages. It was first used in Netscape browsers. JScript performs a similar function for Internet Explorer.

Where did it originate?

Both Javascript and JScript are implementations of ECMAScript, which was announced by the European Computer Manufacturers Association (ECMA) in 1998, as a standard Internet scripting language.

The ECMAScript standard defines a core set of objects for scripting in Web browsers, including manipulating HTML (Hypertext Markup Language) documents. The ECMA-262 standard was actually based on Javascript 1.1. ECMAScript is supposed to have resolved the "minor incompatibilities" in scripting between different browser implementations - though experience suggests that these are far from fully resolved.

Where is it used?

Javascript is aimed both at professional Web developers and users who want to do a little script writing of their own.

What's it for?

Javascript, an extension to HTML, is an object-based scripting language for client and server Web applications. Scripting languages are used to write code that is embedded in an HTML page, and executed by an interpreter to control parts of Web pages after they have been downloaded to the browser.

What makes it special?

It transforms static HTML pages with animation and interactivity, displaying messages, changing colours, kicking off animations or sounds, or validating the data users enter-in forms.

How difficult is it?

Javascript resembles Java, but is much simpler to use. It has been compared with Hypertalk and Dbase, and tools for writing macros for spreadsheets.

Don't confuse

ECMAScript, a scripting language standard, with eczema script, a prescription for a skin complaint.

What does it run on?

The non- (or anti-) Microsoft technology camp has embraced Javascript wholeheartedly. It is extensively used, for example, with IBM's Lotus Domino release 5.

With the ECMA standard, Javascript should be compatible with a wide range of hosts. Each browser and server that supports ECMAScript supplies its own host environment, completing the ECMAScript execution environment.

However, IBM's Developerworks site warns that while the design of the client side of a Web application depends on which technology is employed, you cannot choose your client technology without also considering the server side of your application. "If your server depends on Javascript and complex DHTML, your client should be able to handle them. In other words, the client and server choices must be made as part of an end-to-end design," it says.

Few people know

One football team famous for its lucrative Web site also has its own scripting language called ManUscript.

What's coming up?

Javascript Beans (.jsb). These are pieces of code similar to Java Beans, but using a script and file format that resembles HTML.

Training and rates of pay

You can go to one of the independent training companies and pay £1,000 for a three-day "Web programming with Javascript" course, or you can go on the Web and look for a free tutorial - there are dozens. Try netscape.com, jsworld.com, webcode.com orjavascripts.com.

However, remember that to remain competitive training companies have to ensure that their courses are accurate and up-to-date, while some Internet materials have turned cyber-yellow with age. You could also get up and earning faster with a tutor-led course, which makes it worth the investment.

Web developers with Javascript have been offered up to £140,000, however, £25,000 to £40,000 is more usual.