JavaScript as a Primary Development Language for AJAX applications

JavaScript is a powerful scripting language, but deserved or undeserved, it has gained a bad reputation. If you take some time to look at JavaScript with a fresh eye, you will notice that most of its problems no longer exist. The core language is now standardized with the European Computer Manufacturer's Association (ECMA) standards group and is supported on all modern browsers. Of course, these browsers also support older proprietary syntaxes, and you should avoid these as much as possible. Keeping to the standardized interfaces, JavaScript is portable with a minimal amount of testing and browser-specific code. Because of this standardization, writing complex JavaScript, which was close to impossible in the Netscape 4 days, is now an easy task, although each browser will still need its own testing.

High-quality libraries help reduce the amount of JavaScript you need to write. Many libraries, both open source and commercial, are immature, but the more popular ones are already usable tools, even though it can be harder to find documentation and examples for them than for server-side libraries. JavaScript libraries are especially useful for complicated user-interface elements, such as drag and drop. However, with less-complex elements, such as AJAX communications or visual effects (such as fading an element out), they are less useful because you still have to write all the glue, and that's a large part of the overall code. As AJAX becomes more popular and libraries mature, more and more solutions will be created that will generate all the JavaScript for you, allowing you to handle all the details from your primary development language.

JavaScript's greatest advantage is that it runs directly on the client, so it can react immediately to the user's actions. This interaction allows a JavaScript-driven Web application to offer a highly interactive user experience. The experience is interactive because tasks such as reordering a record no longer take an entire page reload. This direct interaction has driven the development of the language, focusing it on interacting with the HTML DOM. JavaScript's ability to add functions to elements of the page at runtime provides a different programming experience than most other languages. However, its position in the browser gives it the unique opportunity to provide compelling user experience opportunities, especially when teamed with the server communication opportunities that AJAX provides.

Just as with any new language, JavaScript will seem more familiar once you've used it on a couple of different projects. In most cases, the biggest problem isn't dealing with the language, or even the differences in its implementation between browsers, but dealing with the new development paradigm that AJAX brings. Splitting your application into two partsone written in JavaScript and the other written in your normal server languageisn't without costs or problems.