Example of client side programming

 

Over the years there have been various developments on the client-side programming. Netscape started with introducing JavaScript to implement client-side functionality, then Microsoft introduced VBScript. Following are some examples of languages to implement client-side programming.

Java Applets

Java applets represent a compromise between power and security risks. Applets are downloaded by the browser and are run within a virtual machine on the browser. An applet is restricted by the browser security which generally, in theory at least, forbids applet access to local hardware directly or establishing a new Internet connection. Otherwise an applet can do most of what a regular Java program can do; real time graphics, threads, etc. Proponents claim that it is a write once, run anywhere language. Reality is that each browser behaves slightly differently; applets that run reliably on one Windows browser may crash the same browser on Linux. The most common example of a Java Applet is the Java version of the Yahoo messenger.

 

JavaScript

JavaScript is a powerful, object-based scripting language, which is lines of executable computer code, inserted into an HTML page. It allows you to create dynamic, interactive websites that run with the client browser.

JavaScript is an open scripting language that anyone can use without purchasing a license.

JavaScript is supported by all major browsers like Netscape and Internet Explorer

When a JavaScript is inserted into an HTML document, the Internet browser will read the HTML and interpret the JavaScript. The JavaScript can be executed immediately or at a later event.

HTML authors are normally not programmers, but JavaScript is a very light programming language with a very simple syntax! Almost anyone can start putting small code "snippets" into their HTML documents.

Most common implementation of a JavaScript is to validate data entered by the user.

 

VBScript

VBScript is a somewhat simplified version of its superset, Visual Basic for Applications. Therefore, VBScript programming has many similarities to Visual Basic for Applications programming. VBScript has been developed by Microsoft and uses some Microsoft API's to implement advanced features. But this advanced functionality brings with it browser compatibility problems, these features are only available in MS Internet Explorer. So one has to be careful when designing client-side functionality in VBScript as your page won't display properly in other browsers.

 

Flash files

Macromedia Flash is a dynamic multimedia graphics program specially for use on the Web. Its capabilities range from creating simple graphics to complex full featured web sites and interactive movies.


Flash uses vector graphics, which means that the graphics can be scaled to any size without losing clarity/quality something only vector-based graphics allow you to do. Bitmap images on the other hand aren't scalable at all and when enlarged, they can look quite different than what they were intended to look like, like the example below demonstrates.

 

 



Vector Graphic



Bitmap Image

 

The beauty of flash is that you can create games or movie very easily. Because Flash is vector based the movies are pretty small. Normally, when you use an animated gif (or even a bitmap), every pixel is defined. When it's vector based you'll only have a few functions and you need a program to interpret these functions, which is the flash player.


Making movies is pretty easy. Especially with all the build-in drag-and-drop effects, you can create great animations.

 

Flash is basically used to produce mainly vector-based presentations, introductions, corporate presentations and full sites. Its popularity stems from its unique ability to deliver crisp sound and colourful, animated, eye-pleasing graphics to viewers around the world.

 

Director Shockwave

Shockwave is another product from the Macromedia Stable. Shockwave is used for presenting rich-media solutions. It is basically used for developing 3D games, learning applications and streaming video. Usually shockwave is used for developing full fledged games, but one can use shockwave to program client side presentations.

 

DHTML

Dynamic HTML is a combination of technologies to make Web pages dynamic. To most people Dynamic HTML means a combination of HTML 4.0, Style Sheets and JavaScript.