Using this utility you can begin writing ECMAScript 4 code today, receiving its full benefits (such as IDE integration and compile-time type-checking) while still being able to run the resulting code in all modern browsers.
A simple demonstration is up on the Mascara web site which provides a view into the translated source code, along with run-time (and inline) error messages.
A full break-down of the features currently supported are:
- Type verification
- Classes and inheritance, constructors, super initializers
- Static members
- Type inference from initialization
- Parameterized types, Map and Vector
- Union types
- Structural types
- Nullable types
Definitely be aware, however, that while the above feature list is more than enough to get started there are still a a few items left to be implemented.
The most important question, when looking at the above code, should be: How do I begin using this today? Olav went ahead and made it easy to do IDE integration – even setting up instructions on how to integrate with Eclipse on Windows (he currently shows how to integrate using the JScript command-line interface, but it can easily be expanded). I’m quite excited by this prospect – having the ability to do compile-time type-checking and be able to succinctly write classes with inheritance will be a major boon to development.
Additionally, he provides information on how to do automatic CGI translation (naturally, you would want to do this only in a development environment).
He’s continuing to provide frequent updates on the Mascara blog – be sure to follow along if you’re interested in starting to use ECMAScript 4 sooner, rather than later.