Did someone try to compile Zebra Crossing (ZXing) to JavaScript using Emscripten? I searched a lot, but sadly didn't find anyone who succeeded. And I don't have enough knowledge about C++ to try it myself.
The C++ version of ZXing is no longer maintained. Unless you really need everything clientside, I'd just go wrap the Java library in a RPC like Thrift and bolt it in to your backend.
