The problem is, you'll end up porting those language's Garbage Collectors as well. I don't think it's that practical to compile GC'ed languages to asm.js until

The problem is, you'll end up porting those language's Garbage Collectors as well. I don't think it's that practical to compile GC'ed languages to asm.js until GC support is added. The GCs that are in Firefox and Chrome are very efficient low pause collectors, and IMHO, you really don't want to reimplement collector in JS, especially since you can't take advantage of OS/MMU features, and can't do multithreaded collection, etc. Also, if you consider something like the Java Virtual Machine, it's practical to make it work on NaCL, but JS doesn't support blocking/synchronous calls, and how earth would you make all of those synchronous APIs, and multithreaded APIs work in that context? asm.js is not isomorphic to NaCL in terms of feature set, but asm.js + something like OpenCL could probably work well for games.