FAQ Are you really porting the entire Lua VM? Yes: The entire Lua 5.2.4 codebase written in C is compiled to JavaScript here, including a full incremental GC and everything else. It fits in 170K of gzipped JavaScript. How can a VM running in a VM be fast? Lua is implemented in portable C. It is possible to run C compiled to JavaScript at speeds approaching that of a native build (using the asm.js