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JavaScript is the name of Netscape Communications Corporation's
implementation
of ECMAScript, a scripting programming language based on
the concept of prototypes. The language is best known for its use in
websites, but is also used to enable scripting access to objects
embedded in other applications.
Despite the name, JavaScript is only distantly related to the Java
programming language, the main similarity being their common debt to the
C programming language. JavaScript has far more in common with the Self
programming language.
JavaScript is a registered trademark of Sun Microsystems, Inc., used
under license for technology invented and implemented by Netscape.
History
JavaScript was originally developed by Brendan Eich of Netscape
Communications Corporation under the name Mocha, then LiveScript, and
finally renamed to JavaScript. The change of name from LiveScript to
JavaScript roughly coincided with Netscape adding support for Java
technology in its Netscape Navigator web browser. JavaScript was first
introduced and deployed in the Netscape browser version 2.0B3 in
December of 1995. When web developers talk about using JavaScript in
Internet Explorer, they are actually using JScript. The choice of name
proved to be a source of much confusion.
As of 2005, the latest version of the language is JavaScript 1.6,
which corresponds to ECMA-262 Edition 3 like JavaScript 1.5, except for
Array extras, and Array and String generics. ECMAScript, in simple
terms, is a standardized version of JavaScript. The ECMA-357 standard
specifies E4X, a language extension dealing with XML.
Usage
JavaScript is a prototype-based scripting language with a syntax
loosely based on C. Like C, the language has no input or output
constructs of its own. Where C relies on standard I/O libraries, a
JavaScript engine relies on a host environment into which it is
embedded. There are many such host environment applications, of which
web technologies are the most well known examples. These are examined
first.
One major use of web-based JavaScript is to write functions that are
embedded in or included from HTML pages and interact with the Document
Object Model (DOM) of the page to perform tasks not possible in HTML
alone. Some common examples of this usage follow.
- Opening or popping up a new window with programmatic control over
the size, position and 'look' of the new window (i.e. whether or not
the menus, toolbars etc are visible. Usually JavaScript is used to
ensure that they are not)
- Checking or validating web form input values to make sure that
they will be accepted before they are submitted to the server
- Changing images as the mouse cursor moves over them
Unfortunately, the DOM interfaces in various browsers differ and don't
always match the W3C DOM standards. Rather than write different variants
of a JavaScript function for each of the many browsers in common use
today, it is usually possible, by carefully following the W3C DOM Level
1 or 2 standards, to provide the required functionality in a
standards-compliant way that most browsers will execute correctly. Care
must always be taken to ensure that the web page degrades gracefully and
so is still usable by any user who
- has JavaScript execution disabled - for example as a security
precaution
- has a browser that does not understand the JavaScript - for
example on a PDA or mobile phone
- is visually or otherwise disabled and may be using an unusual
browser, a speech browser or may have selected extreme text
magnification. For more information on this, see the Web
Accessibility Initiative
Other examples of JavaScript interacting with a web page's DOM have
been called DHTML and SPA.
A different example of the use of JavaScript in web pages is to make
calls to web and web-service servers after the page has loaded,
depending upon user actions. These calls can obtain new information,
which further JavaScript can merge with the existing page's DOM so that
it is displayed. This is the basis of Ajax programming.
Outside of the Web, JavaScript interpreters are embedded in a number
of tools. Adobe Acrobat and Adobe Reader support JavaScript in PDF
files. The Mozilla platform, which underlies several common web
browsers, uses JavaScript to implement the user interface and
transaction logic of its various products. JavaScript interpreters are
also embedded in proprietary applications that lack scriptable
interfaces. Dashboard Widgets in Apple's Mac OS X v10.4 are implemented
using JavaScript. Microsoft's Active Scripting technology supports
JavaScript-compatible JScript as an operating system scripting language.
JScript .NET is a CLI-compliant language that is similar to JScript, but
has further object oriented programming features. Tools in the Adobe
Creative Suite, including Photoshop, allow scripting through JavaScript.
Each of these applications provides its own object model which
provides access to the host environment, with the core JavaScript
language remaining mostly the same in each application. [Source: Wikipedia]
Links
Javascripts.com : Hundreds of
javascripts, news, articles to enhance your website looks and performance.
ScriptSearch: ScriptSearch.com serves the Internet community as the largest and most well-known programming directories anywhere. Now owned by internet.com Corporation (formerly Mecklermedia Corporation), the ScriptSearch site has undergone a complete redesign and relaunch in early 2001 in order to better tune the site for you, the visitor.ScriptSearch's comprehensive programming directory is more intuitively organized by programming language with subfolders with various script categories.
The Javascript Source - The JavaScript Source is an excellent JavaScript resource with tons of "cut and paste" JavaScript examples for your Web pages. All for free! We have put together a collection of hundreds of free JavaScripts that are available to you for use on your web pages. The scripts are available via a user friendly interface -- including a working JavaScript example of all the scripts and a text box with the complete actual JavaScript code used. We also have a great JavaScript books section if you would like to learn JavaScript, and a JavaScript Help Forum where you can post script requests, script questions, and more. Check it out! CodeLifter.com Free JavaScript Archive
: Ya gotta get a look at these really great web effects that you can quickly and easily insert into your page. CodeLifter is a CodeBrain.com Sister Site. CodeBrain.com: : The CodeBrain site is comprised of some 450+ pages, devoted to JAVA,
Perl, JavaScript, and web site development resources and issues. Contains very useful ready to use java applets for your use. Some of the applets are for sale and some are free to download. CodeBrain is constantly adding new scripts, applets, and software. If you do not receive our newsletter, now might be a good time to subscribe. Dynamic Drive No fluff. Just a lot of great DHTML scripts. Welcome to Dynamic Drive, the premier place on the net to obtain free,
original DHTML scripts and components to enhance your web site. All scripts on this site take advantage of the latest in JavaScript and DHTML technology, with emphasis on practicality and backwards compatibility, to bring true power and interactivity to your site. Enjoy! Java-Scripts.net - Welcome to
Java-scripts.net, a great little place to find cool and useful JavaScripts for your site! All scripts on this site come with easy-to-follow installation instructions, along with a live demonstration. Want some free traffic? Submit your free javascript to us and we will add it to our archive and link it back to your site. Want to learn
javascript? Now you can! Get started with this site navigation
tutorial. JavaScript City - A guide to free
JavaScripts, tutorials, and resources. Find free cut and paste JavaScripts to add to your site to perform various tasks. Instructions on how to install and use the scripts are included with most of the scripts. JavaScript Tutorials on cut and paste JavaScript topics, plus links to sites which teach you how to write javascripts on your own. Also include JavaScript Discussion Forums, Information and Documentation Sites which offer information on the JavaScript language, Script Submission option and more. JavaScript
Toolbox - This site is intended to be a repository of code and
reusable libraries which address common needs that many web developers
encounter. The code found here is based on standards but also tries to
be backwards-compatible for browsers which don't support the standards. Nic's JavaScript Here at Nic's JavaScript Page, we do things a little differently than
the competition. Unlike other other JavaScript pages that try to junk their examples full of useless code, we prefer to make our codes as small as possible. This makes the code easier to manipulate and learn from. We have had many e-mails from people who taught themselves JavaScript just by looking at our examples. Also unlike the competition, we only like to have one or two of a certain type of script. This helps the viewer find the code he wants faster. Come in and look at all the 95 unique examples we have to offer here, categorized by subject. JavaScript Kit - Formerly Website Abstraction, JavaScript Kit offers Scripts, JS tutorials, Advanced JS
tutorials, Applets, Web Tutorials, DHTML, Forum and Freewarejava. ZDNet Developer ScriptLibrary -
ZDNet, www.zdnet.com, operates a worldwide network of web sites that offer content, services, and commerce opportunities that enable IT professionals and business influencers to gain an edge in business. Winner of the Computer Press Association's "Best Overall Site" award for two consecutive years, ZDNET provides an invaluable perspective and resources so that users can get the most out of their investments in technology. HotScripts.com HotScripts.com is an
Internet directory that compiles and distributes Web programming-related resources. HotScripts.com is geared toward webmasters and programmers who are looking to enhance their Web sites and intranets with dynamic development tools. With thousands of Web programming resources available on the Internet today, our mission is to provide Web developers with the best collection of quality programming information and resources in the most convenient fashion.
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