用golang解析Perl正则表达式

This is my code and playground.

func insert_comma(input_num int) string {
    temp_str := strconv.Itoa(input_num)
    var validID = regexp.MustCompile(`\B(?=(\d{3})+$)`)
    return validID.ReplaceAllString(temp_str, ",")
}

 func main() {
    fmt.Println(insert_comma(1000000000))
 }

Basically, my desired input is 1,000,000,000. And the regular expression works in Javascript but I do not know how to make this Perl regex work in Go. I would greatly appreciate it. Thanks,