JavaScript and Other Client-Side Technologies
The various client-side technologies differ in many ways, starting with the way they get loaded and executed by the web client. JavaScript is a scripting language, whose code is written in plain text and can be embedded into HTML pages to empower them. When a client requests an HTML page, that HTML page can contain JavaScript. JavaScript is supported by all modern web browsers without requiring users to install new components on the system.
JavaScript is a language in its own right (theoretically it isn’t tied to web development), it’s supported by most web clients under any platform, and it has some object-oriented capabilities. JavaScript is not a compiled language so it’s not suited for intensive calculations or writing device drivers and it must arrive in one piece at the client browser to be interpreted so it is not secure either, but it does a good job when used in web pages.
With JavaScript, developers could finally build web pages with snow falling over them, with client-side form validation so that the user won’t cause a whole page reload (incidentally losing all typed data) if he or she forgot to supply all the details (such as password, or credit card number), or if the email address had an incorrect format. However, despite its potential, JavaScript was never used consistently to make the web experience truly user friendly, similar to that of users of desktop applications.
Other popular technologies to perform functionality at the client side are Java applets and Macromedia Flash. Java applets are written in the popular and powerful Java language, and are executed through a Java Virtual Machine that needs to be installed separately on the system. Java applets are certainly the way to go for more complex projects, but they have lost the popularity they once had over web applications because they consume many system resources. Sometimes they even need long startup times, and are generally too heavy and powerful for the small requirements of simple web applications.
Macromedia Flash has very powerful tools for creating animations and graphical effects, and it’s the de-facto standard for delivering such kind of programs via the Web. Flash also requires the client to install a browser plug-in. Flash-based technologies become increasingly powerful, and new ones keep appearing.
Combining HTML with a server-side technology and a client-side technology, one can end up building very powerful web solutions.