Prerequisites

• Emscripten: https://emscripten.org/docs/getting_started/downloads.html
• NodeJS: https://nodejs.org/en/download/
• Python3: https://www.python.org/downloads/

Steps

• Set up emscripten (see prerequisites) and make sure the compiler is present: which emcc

• Compile rand_gen.cpp to WASM (one of the following options):

  1. Bare metal: emcc -lembind -DENABLE_WASM -o rand_gen_c.js rand_gen.cpp.
  2. Docker compilation: docker run --rm -v $(pwd):/src -u $(id -u):$(id -g) emscripten/emsdk emcc -lembind -DENABLE_WASM -o rand_gen_c.js rand_gen.cpp

  This should generate gen_rand_c.wasm file with WebAssembly code and gen_rand_c.js with JS "glue" code.

• dice_roll.js imports the glue code which instantiates WASM module and runs a function compiled to WASM from C++: node dice_roll.js

• test.html also runs this function but in the web environment, emulating a frontend environment: python3 -m http.server, then open browser at http://localhost:8000/test.html. In console (ctrl+shift+c) the random number generation is visible (try refreshing for random testing)