Golang : How to determine if user agent is a mobile device example

With the increasing number of people accessing the Internet with mobile devices such as tablet or smart phone apart from desktop. The ability to detect which devices that your visitor is using to visit your web site/app is crucial. Once you're able to detect the correct device, you can then customize the UX or other feature specifically for the devices.

For this tutorial, we will create a function to determine if a user agent is a mobile device (iPad, Android, etc) or not.

Here you go!

 package main

 import (
  "fmt"
  "net/http"
  "strings"
 )

 func is_mobile(useragent string) bool {
  // the list below is taken from
  // https://github.com/bcit-ci/CodeIgniter/blob/develop/system/libraries/User_agent.php

 mobiles := []string{"Mobile Explorer","Palm","Motorola","Nokia","Palm","Apple iPhone","iPad","Apple iPod Touch","Sony Ericsson","Sony Ericsson","BlackBerry","O2 Cocoon","Treo", "LG", "Amoi", "XDA", "MDA", "Vario", "HTC", "Samsung",
  "Sharp", "Siemens", "Alcatel", "BenQ", "HP iPaq", "Motorola", "PlayStation Portable", "PlayStation 3", "PlayStation Vita", "Danger Hiptop", "NEC", "Panasonic", "Philips", "Sagem", "Sanyo", "SPV", "ZTE", "Sendo", "Nintendo DSi", "Nintendo
  DS", "Nintendo 3DS", "Nintendo Wii", "Open Web", "OpenWeb", "Android", "Symbian", "SymbianOS", "Palm", "Symbian S60", "Windows CE", "Obigo", "Netfront Browser", "Openwave Browser", "Mobile Explorer", "Opera Mini", "Opera Mobile", "Firefox
  Mobile", "Digital Paths", "AvantGo", "Xiino", "Novarra Transcoder", "Vodafone", "NTT DoCoMo", "O2", "mobile", "wireless", "j2me", "midp", "cldc", "up.link", "up.browser", "smartphone", "cellphone", "Generic Mobile"}

  for _, device := range mobiles {
 if strings.Index(useragent, device) > -1 {
 return true
 }
  }
  return false
 }

 func checkIfUserAgentIsAMobile(w http.ResponseWriter, r *http.Request) {
  ua := r.Header.Get("User-Agent")

  fmt.Printf("user agent is: %s \n", ua)
  w.Write([]byte("user agent is " + ua + "\n"))

  result := "no"

  if is_mobile(ua) {
 result = "yes"
  }

  fmt.Printf("user agent is a mobile: %v \n", is_mobile(ua))
  w.Write([]byte("user agent is a mobile:" + result + "\n"))

 }

 func main() {
  http.HandleFunc("/", checkIfUserAgentIsAMobile)
  http.ListenAndServe(":8080", nil)
 }

Sample output:

from a visit by iPad:

user agent is Mozilla/5.0 (iPad; CPU OS 921 like Mac OS X) AppleWebKit/601.1 (KHTML, like Gecko) CriOS/47.0.2526.107 Mobile/13D15 Safari/601.1.46

user agent is a mobile:yes

from a Mac:

user agent is Mozilla/5.0 (Macintosh; Intel Mac OS X 1085) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.116 Safari/537.36

user agent is a mobile:no

References:

https://github.com/bcit-ci/CodeIgniter/blob/develop/application/config/user_agents.php

https://socketloop.com/tutorials/golang-check-if-user-agent-is-a-robot-or-crawler-example