We're now offering TypeScript as a JavaScript preprocessor on CodePen! TypeScript is a superset of JavaScript, meaning it's the same syntax as JavaScript and supports everything JavaScript does, but also does more.

It's developed by Microsoft, who adds:

TypeScript offers classes, modules, and interfaces to help you build robust components.

These features are available at development time for high-confidence application development, but are compiled into simple JavaScript.

We've long wanted to add TypeScript to CodePen, but were particularly motivated to get it done when it was revealted that Angular 2 will be written in TypeScript. There are a heck of a lot of Angular developer out there, so perhaps there we be a lot more people interested in working with TypeScript. Now you can, enjoy!

Here's their Hello World:

See the Pen XbjXXW by Chris Coyier (@chriscoyier) on CodePen.

Here's the To Do demo they offer:

See the Pen TypeScript ToDo MVC by Chris Coyier (@chriscoyier) on CodePen.