The real Go compiler and linker, built for js/wasm, run below against an in-memory filesystem. Edit the program and rebuild — nothing after page load touches the server. Imports are limited to the packages seeded from the manifest (the fmt/os/runtime closure).
More, going up in ambition:
probe-gobuild.html — the
real cmd/go running a full go build from
standard-library source;
probe-gonet.html — the
same, of a module fetched from the network. The network one needs a server for
its /goproxy passthrough (go run ./serve/main.go), so
it won't complete on static hosting like GitHub Pages — run it locally.