Actually, you can build small portions of an app with it. That's pretty much all you can do with it, for the very reasons you stated: no JS object access, no st

Actually, you can build small portions of an app with it. That's pretty much all you can do with it, for the very reasons you stated: no JS object access, no strings, etc. All you can do is the same stuff you'd need assembly for anyway: super-tight inner loops that work over lots and lots of raw numeric data. That's an important part of compiling C and C++ applications to run in the browser efficiently, but it's only one small part of the puzzle. C and C++ compilers put a lot of work into optimizing this same sort of code, and asm.js gives them a path to bring some of those optimizations to the browser. But no C/C++ application, even compiled with emscripten or the like, is ever going to be compiled solely to pure asm.js. It's just one part of a larger equation.