code: func findGopherJSGoroot() (string, error) {
  	dir, err := os.Open(homeDir())
  	if err != nil {
  		return "", err
  	}
  	defer dir.Close()
  	names, err := dir.Readdirnames(-1)
  	if err != nil {
  		return "", err
  	}
  	goVersion := fmt.Sprintf("go1.%d", gopherJSGoMinor)
  	for _, name := range names {
  		if strings.HasPrefix(name, goVersion) {
  			return name, nil
  		}
  	}
  	return "", nil
  }
docs: // findGopherJSGoroot tries to find a go1.gopherJSGoMinor.* go root in the home
  // directory. It returns the empty string and no error if none was found.