First, please install Emscripten. You can follow the instructions to install Emscripten on their website: http://kripken.github.io/emscripten-site/docs/getting_started/downloads.html#sdk-download-and-install
You will then need to run npm install.
To build the application, you can run npm run wasm, which will generate the WebAssembly code.
Afterward, run ng build to build the Angular application with the WebAssembly code.
The development pattern is similar to the build, except you will need to run ng serve instead.