(had a look, couldn't recall this having been discussed or raised before)

Consider the following code:

package main

import (
	"fmt"
)

type S struct {
	Name string
}

func (s S) SetName(n string) {
	s.Name = n
}

type NameSet interface {
	SetName(n string)
}

func main() {
	s1 := S{}
	var s2 NameSet = s1
	s1.Name = "Rob"
	
	fmt.Printf("s1: %v, s2: %v\n", s1, s2)
	
	s2.SetName("Pike")
	fmt.Printf("s1: %v, s2: %v\n", s1, s2)
}

Per the Go Playground, this should output:

s1: {Rob}, s2: {}
s1: {Rob}, s2: {}

But per the GopherJS Playground we get:

s1: {Rob}, s2: {Rob} 
s1: {Pike}, s2: {Pike} 

Reason being the assignment to s2 is not $clone-ing the value from s1.

Similarly, in the call s2.SetName we are not $clone-ing.

If the type of s2 is changed to S then everything works as expected.

Will look into this a bit more later, just logging here for now.