Tutorial: Introduction to JavaScript

JavaScript is an easy-to-learn programming language which can be built into Web pages, so that it executes from within the browser rather than on the web server. Intranets especially can leverage the power of JavaScript to create "smart" Web pages which can process data and interact with the user. In this introduction we concisely look at the main programming points of the JavaScript language.

Versions of JavaScript

There are several versions of JavaScript supported by certain browsers and browser versions. Unfortunately, this can often lead to confusion and incompatibilities. Since Netscape originally introduced JavaScript, JavaScript 1.0 was the language specification supported in Netscape Navigator 2.0. Subsequently, Navigator 3.0 supported new enhancements which comprised JavaScript 1.1. At present, Navigator 4.0 versions below 4.05 inclusive support JavaScript 1.2 while Navigator 4.06+ and the Netscape Communicator 4.5+ series support JavaScript 1.3.

Shortly after Netscape's introduction of JavaScript in Navigator 2.0, Microsoft attempted to support JavaScript 1.0 in their Internet Explorer 3.0 browser. Known as "Jscript," Microsoft's initial JavaScript support was unreliable and buggy. A push to standardize the language resulted in an "official" version of JavaScript sanctioned by the ECMA, an international standards body. Both Internet Explorer 4.0 JScript and Netscape's JavaScript 1.3 are ECMA-compliant and therefore the most compatible with one another. Internet Explorer 5 introduces additional extensions to the present ECMA standard which are not yet supported in kind by Netscape.

As you can see, the ongoing browser war takes a great toll on web development at the JavaScript level. Because of the variation in support for JavaScript/JScript across browser revisions, and quite a few exceptions therein, it is impossible to say that any two browser versions are completely compatible with one another. For many web developers, authoring JavaScript code which gracefully accounts these in JavaScript support is an enormous challenge. Intranet developers may have the unique advantage of being able to focus on a single version of JavaScript in the case of intranets where only a single version of a single browser is deployed. From the developer's perspective, this type of intranet policy greatly eases the web development process, increasing both functionality and speed of development.