can i let javascript call native function?

[rocket049]

my code not run correct.

//tryit.go
package main

import (
	"flag"
	"os"
)
import (
	"log"

	"github.com/gotk3/gotk3/glib"
	"github.com/gotk3/gotk3/gtk"
	"github.com/sourcegraph/go-webkit2/webkit2"
	"github.com/sqs/gojs"
)

func JsNative(s string) *gojs.Value {
	log.Printf("JS native : %s\n", s)
	return nil
}

func main() {
	flag.Parse()
	gtk.Init(&os.Args)
	win1, _ := gtk.WindowNew(gtk.WINDOW_TOPLEVEL)
	defer win1.Destroy()
	web1 := webkit2.NewWebView()
	defer web1.Destroy()
	win1.Add(web1)
	web1.Context().SetCacheModel(webkit2.WebBrowserCacheModel)
	web1.Settings().SetAutoLoadImages(false)
	web1.SetVisible(true)
	jscxt := web1.JavaScriptGlobalContext()
	js1 := jscxt.NewFunctionWithNative(JsNative)
	err := jscxt.SetProperty(jscxt.GlobalObject(), "jsNative1", js1.ToValue(), gojs.PropertyAttributeReadOnly)
	if err != nil {
		log.Println(err)
	}
	web1.Connect("load-failed", func() {
		log.Println("Load failed.")
	})
	web1.Connect("load-changed", func(_ *glib.Object, i int) {
		loadEvent := webkit2.LoadEvent(i)
		switch loadEvent {
		case webkit2.LoadFinished:
			web1.RunJavaScript("jsNative1('abcd')", func(result *gojs.Value, err error) {
				log.Println("jsNative1:", err)
				gtk.MainQuit()
			})
		}
	})
	URL := flag.Arg(0)
	glib.IdleAdd(func() bool {
		web1.LoadURI(URL)
		return false
	})
	gtk.Main()
}

i build it and run, the result is like follow:

./tryit https://www.baidu.com/
2018/11/01 16:19:29 jsNative1: TypeError: undefined is not a function