This is a starting point for an imo not-so-uncommon use of WebAssembly: having the user select a file, processing it, and then rendering a template based on the result, all inside the browser. For example, I'm working on something like that for parsing Warcraft 3 replays.
In this case, we print the length of the file and the first line if the contents are a valid UTF-8 string.
It embeds the template inside the binary using github.com/jerblack/statics (or rather my 1-commit-ahead fork), and defers file processing until the WebAssembly program has initialized.
Run make in the root directory to build, and serve the public/ directory with something like:
# install goexec: go get -u github.com/shurcooL/goexec
$ goexec 'http.ListenAndServe(`:8080`, http.FileServer(http.Dir(`.`)))'Make sure the server supports the application/wasm Content-Type. Then you can deploy the folder on some static host/cdn like netlify.
Also take a look at this rather helpful overview: https://github.com/golang/go/wiki/WebAssembly