AFAIK you cannot access the DOM from WebAssembly right now, although it probably will come in future versions.

But you can use the WebAssemblyExplorer https://mbebenita.github.io/WasmExplorer/: There is also a nice video about using WebAssemblyExplorer and even uses a simple WebAssembly-Module: https://www.youtube.com/watch?v=3XrGjSnPHGY&t=310s