type foo struct {
	*js.Object
	bar bool `js:"bar"`
}
type t struct {
	*js.Object
	*foo `js:"foo"`
}

t1 := t{Object: js.Global.Get("Object").New()}
t1.foo = nil

// => "t1.foo != nil"
if t1.foo == nil {
	fmt.Println("t1.foo == nil")
} else {
	fmt.Println("t1.foo != nil")
}
fmt.Printf("t1.foo is %v\n", t1.foo) // => "t1.foo is null"

// => "t1.foo != itself"
if t1.foo == t1.foo {
	fmt.Println("t1.foo == itself")
} else {
	fmt.Println("t1.foo != itself")
}