Actually, a lot of the useful things like ADT illustrations tend to be written as ancient Java applets as well.<p>On the other hand, the Java bytecode is simple enough that it shouldn&#x27;t be too much work to write an emulator in JS, and, as most of Java is written in Java, all one really needs to write around that is a shell for the AWT and maybe a bit of class&#x2F;string functionality to get the viewer working. Threading and I&#x2F;O would be a truly nasty pain, but you could probably bypass most of that.<p>I&#x27;d be more surprised if there weren&#x27;t already some attempts to work on this.