JS bindings (GopherJS)

Hi,

I'm trying to create a wrapper for a node js support using the `go-jsonnet` version of jsonnet rather than the the C++ version. I'm trying to use `gopherjs` to transpile `go-jsonnet` which can be used for node.js applications. I'm hoping by doing this, it will prove faster than the C++ version using emscripten and 🤞will also support imports.

I have an example go app setup following some advice from this [article](https://medium.com/@kentquirk/how-to-use-gopherjs-to-turn-go-code-into-a-javascript-library-1e947703db7a)

```go
package main

//go:generate gopherjs build --minify

// This is an experiment to see if gopherjs can reasonably generate js code from go source
// so that we can have a single-source solution for keys and addresses.
// Use "go generate" to build this.

import (
"crypto/sha256"

"github.com/gopherjs/gopherjs/js"
)

func main() {
js.Module.Get("exports").Set("hashit", hashit)
}

func hashit(s string) []byte {
h := sha256.New()
h.Write([]byte(s))
return h.Sum(nil)
}
```
However I'm unsure what I need to reference from jsonnet after following these instructions:

```bash
git clone github.com/google/go-jsonnet
cd go-jsonnet
go build ./cmd/jsonnet
```
Is there any chance anyone can point me in the right direction?