JavaScript » Introduction

Welcome to the DevGuru JavaScript Quick Reference guide. This is an extensive reference source that explains and gives comprehensive, working examples of code in a definitive manner for the JavaScript language (and hence, for the ECMAScript and JScript languages). All elements of the language are covered, including the events, functions, methods, objects, operators, properties, statements, and values.

The JavaScript language was developed by the Netscape Communications Corporation and is a trademarked name. It is a cross-platform, object-based scripting language that was originally designed for use in Netscape Navigator. Indeed, versions 2.0, and later, of Navigator can interpret JavaScript statements that are embedded within HTML code. When a request is made to see a page, the HTML code that defines the requested page along with the embedded JavaScript statements, are sent by the server to the client. Navigator interprets the HTML document and executes the JavaScript code. The resultant page is displayed for the client. It is important to understand that this interpretation occurs on the client-side rather than the server-side.

After the success of JavaScript in Navigator 2.0, the Microsoft Corporation was quick to create a clone of JavaScript, called JScript, which is a trademarked name, that is designed to run inside the Microsoft Internet Explorer. In truth, except for a few minor differences, JScript is essentially a carbon copy of JavaScript. As a consequence, this DevGuru JavaScript Quick Reference will be of value to both JavaScript and JScript users.

The latest versions of JavaScript and JScript are compliant with the European Computer Manufacturing Association's ECMAScript Language Specification (ECMA-262 standard, for short). Note that the name for this ECMA-262 language is ECMAScript. However, Netscape will continue to use the name, JavaScript and, likewise, Microsoft will continue to use the name, JScript. It is important to understand that the ECMA-262 standards sets minimum compatibility requirements. You should expect current and future versions of both JavaScript and JScript to also contain additional proprietary features, beyond the minimum requirements, designed to woo the developer to favor one language over the other. Fortunately, both Microsoft and Netscape have promised to submit new features to ECMA for inclusion in the evolving ECMA-262 standard. Many older browsers are, of course, still very happily utilizing older, non-compliant versions of these scripting languages.

JavaScript is a simple to comprehend, easy to use, general purpose scripting language. When used in conjunction with a Web browser's Document Object Model (DOM), it can produce powerful dynamic HTML browser-based applications which also can feature animation and sound.