Convert string to rune slice

[pgundlach]

With the following code I get an error:

TypeError: could not convert function call parameter 0: could not convert Hello to []int32 at 
  reflect.methodValueCall (native)
exit status 255

My goal is to use a method I cannot change. How would I work around this issue? I guess (as always) I am missing something obvious.

package main

import (
	"fmt"
	"os"

	"github.com/dop251/goja"
)

type document struct {
}

func (d *document) Foo(r []rune) {
	fmt.Println(r)
}

func newDocument() *document {
	d := &document{}
	return d
}

func main() {
	runtime := goja.New()

	gjNewDoc := func(call goja.FunctionCall) goja.Value {
		v := runtime.ToValue(newDocument())
		return v
	}

	runtime.Set("newdoc", gjNewDoc)

	_, err := runtime.RunString(`
var d = newdoc();
d.Foo("Hello")
`)
	if err != nil {
		fmt.Println(err)
		os.Exit(-1)
	}

}

[dop251]

There is no automatic conversion from string to []rune, mainly because unfortunately rune is a type alias for int32 and therefore they can't be distinguished at runtime. And if your function expects[]int32 it does not necessarily mean it expects []rune.

In your specific case you could expose a method to convert a string to []rune, i.e.

runtime.Set("toRunes", func toRunes(s string) []rune {
    return []rune(s)
})
// ...

_, err := runtime.RunString(`
var d = newdoc();
d.Foo(toRunes("Hello"))
`)

[pgundlach]

I see, thank you very much!