Add guard to call javascript function from JS

guard.go

package main

import (
	"fmt"

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

var script = `
  window.Guard = function(caller){
    try { 
      return caller.apply(this, [].slice.call(arguments,1))
   }catch(e){
    return e
   }
 }
`

func main() {
	fmt.Println("Hello, playground")
	fmt.Println("Hello, JS console")

	scriptObj := js.Global.Get("document").Call("createElement", "script")
	scriptObj.Set("textContent", script)

	js.Global.Get("document").Get("body").Call("appendChild", scriptObj)

	js.Global.Call("Guard", func(name string) { js.Global.Get("console").Call("log", "Name:", name) }, "dude")
}