Run Go as WebAssembly

http.go

package main

import (
	"fmt"
	"net/http"
)

// https://github.com/golang/go/tree/master/misc/wasm

func main() {
	http.HandleFunc("/", indexHandler)
	http.HandleFunc("/wasm_exec.js", jsHandler)
	http.HandleFunc("/test.wasm", wasmHandler)

	fmt.Println("running http server")

	http.ListenAndServe(":8000", nil)
}

func indexHandler(w http.ResponseWriter, r *http.Request) {
	http.ServeFile(w, r, "wasm_exec.html")
}

func jsHandler(w http.ResponseWriter, r *http.Request) {
	http.ServeFile(w, r, "wasm_exec.js")
}

func wasmHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/wasm")
	http.ServeFile(w, r, "wasm")
}

wasm.go

package main

import (
	"log"
	"syscall/js"
)

// GOARCH=wasm GOOS=js go1.11beta1 build -ldflags '-w' ./cmd/wasm

func main() {
	var cb js.Callback

	cb = js.NewCallback(func(args []js.Value) {
		log.Println("button clicked")
		// cb.Release() // release the callback if the button will not be clicked again
	})
	js.Global().Get("document").Call("getElementById", "myButton").Call("addEventListener", "click", cb)

	select {}
}