JavaFX Version

This sliding-puzzle started being an experiment to learn the basics of JavaFX. So the first version was desktop-only:


But at the same time I already had heard of Scala.js, so I took care to make the code modular, separating game-logic from the UI as much as possible.

JavaScript UI

During the last DevFest I tried to implement the Scala.js frontend in the course of one afternoon. I made some progress, but was not nearly finished.

My initial approach was to start from a** JavaScript prototype of the UI**, and try to glue it with the existing Scala game-logic later. This approach proved out to be very productive: I could try things, reload and see changes instantly. Soon I had the basic functionality which the game would need:

  • separating the image into tiles
  • event-handling of mouse-clicks
  • moving tiles with animation
  • hiding/showing tiles with animation
  • re-calculating the tiles upon puzzle-size change

But due to “lack of time” (actually, because of other projects) I left this for a while…

Connecting with Scala.js

A couple of days ago, I continued my journey and started to glue the existing Scala.js code with the UI prototype written in JavaScript.

I learned some valuable lessons along the way, like:

  • how to interact with JavaScript code from Scala.js
  • how to write JavaScript calls to 3rd party libraries that can survive Google Closure‘s optimizations
  • about the jQuery and DOM wrappers for Scala.js

Once I got it working, I began to migrate what I had written in JavaScript more and more to the Scala side, until the original JavaScript code completely disappeared ;-)

After some days of hard-work I finally arrived at a version I’m comfortable with:



You can try it out without downloading or installing anything right now, since I made an online demo available here:

And if you are curious about how it was done and how you can use Scala.js to build multi-platform code, or simply develop a browser-based application, you can take a look at the source-code here:

The resulting project compiles both to JavaScript (and uses jQuery under the hood) and as a native JVM application (requires support for JavaFX).

I hope this simple demo gives an idea of what is possible today by writing pure Scala.