So, I used to think that javascript was evil and bad, and made for brittle websites that only worked in one browser. That danger is still present, but its not really the fault of javascript. Sticking to the ECMA and W3C DOM standards should avoid most of the pitfalls.

I’m more interested in Javascript as a language. Its a prototype-based OO language. Prototype based languages don’t have the concept of classes per se, you define types by instantiating objects and then attaching function definitions. Once your prototype object has all the behaviour you want, you can use it as a template to instantiate other objects of the same type. Functions can be defined either as global, or bolted to an object as methods. Functions can also be directly referenced as variables. Function parameters can either be named explicitly, or referenced by indexing into the arguments array. So although a function may state that it takes 2 arguments by saying ‘function foo(bar, baz)’, there’s nothing to stop you calling it with 20 arguments.

What is also very cool is that you can make HTTP requests directly in javascript, and refresh parts of the page independently. This makes it possible to build very interactive portal applications that can update the screen asynchronously without an obvious browser refresh.

The netWindows open source project has a bunch of very useful stuff, including a standalone signals & slots implementation for javascript, which is very handy for building event-driven pages.

Avi Bryant has graciously published some javascript that can selectively replace chunks of HTML based on an asynchronous server call.

The Oddpost guys even built a full fledged 3-pane email application (with drag and drop) inside a web browser. Shame they’re no longer taking subscriptions. I want one!