How to pass custom module from JS to C++

Passing custom module from JS to C++ code with Emscripten is the easier task than it seems!
I created a tiny example to show how to pass module from JS to C++ using Emscripten and val::global()

First of all we need to write a C++ function for the loading. It looks like this:

int loadCustomModule (std::string globalModuleName) {
  val ModuleClass = val::global(globalModuleName.c_str());
    if (!ModuleClass.as<bool>()) {
    std::cout << "No global module " << globalModuleName;
  }
  return 0;
}

Then we need to pass this function to JS using EMSCRIPTEN_BINDINGS:

EMSCRIPTEN_BINDINGS(module) {
  function("loadCustomModule", &loadCustomModule);
}

Yeah, that's all! Now, we can use our loadCustomModule function in JS.

class HelloWorldCustomModule {
    helloWorld() {
        console.log('Hello, World!')
    }
}
var Module = {
    onRuntimeInitialized: function () {
        window.HelloWorldCustomModule = HelloWorldCustomModule;
        Module.loadCustomModule('HelloWorldCustomModule')
    }
};

And the last step is using our HelloWorldCustomModule in C++

int loadCustomModule (std::string globalModuleName) {
  // ... first part is above
  val module = ModuleClass.new_();
  module.call<val>("helloWorld");
  return 0;
}

Compilation

em++ -lembind -o passCustomModule.js passCustomModule.cpp -s ERROR_ON_UNDEFINED_SYMBOLS=0 -Wall --bind

The full example with HTML you can find there