func ResponseWithJSON(w http.ResponseWriter, json []byte, code int) {
    w.Header().Set("Content-Type", "application/json; charset=utf-8")
    w.Header().Set("Access-Control-Allow-Origin", "*")
    w.WriteHeader(code)
    w.Write(json)
}

w.Header().Set("Access-Control-Allow-Origin", "http://www.example.com")

w.Header().Set("Access-Control-Allow-Origin", "http://example.com")

w.Header().Set("Access-Control-Allow-Origin", "http://www.example.com,http://example.com")

w.Header().Set("Access-Control-Allow-Origin", "http://www.example.com")
w.Header().Set("Access-Control-Allow-Origin", "http://example.com")