To make a wasm-based REPL for goal, you have to compile the package to wasm
into a goal.wasm file located in the same directory, along index.html and
style.css.
GOOS=js GOARCH=wasm go build -o goal.wasm
You also need to copy the wasm_exec.js support file corresponding to your Go
version, as explained in Go Wiki:
WebAssembly.
The resulting directory can then be served over HTTP.