Generate map link according to accessing OS

gistfile1.js

/**
 * Determine the mobile operating system.
 * This function returns one of 'iOS', 'Android', 'Windows Phone', or 'unknown'.
 *
 * @returns {String}
 * 
 * Source: http://stackoverflow.com/questions/21741841/detecting-ios-android-operating-system
 */
function getMobileOperatingSystem() {
  var userAgent = navigator.userAgent || navigator.vendor || window.opera;

      // Windows Phone must come first because its UA also contains "Android"
    if (/windows phone/i.test(userAgent)) {
        return "Windows Phone";
    }

    if (/android/i.test(userAgent)) {
        return "Android";
    }

    // iOS detection from: http://stackoverflow.com/a/9039885/177710
    if (/iPad|iPhone|iPod/.test(userAgent) && !window.MSStream) {
        return "iOS";
    }

    return "unknown";
}

/**
 * Generate map uri according to accessing OS
 *
 * @param string|int lat    given latitude
 * @param string|int long   given longitude
 *
 * @return string           generated uri scheme
 */
function generate_map_link(lat, long){
    let device = getMobileOperatingSystem();
    let protocol = "";
    if(device == 'Android'){
      protocol = "geo:";
    }else if(device == 'iOS'){
      protocol = "http://maps.apple.com/?ll=";
    }else if(device == 'Windows Phone'){
      protocol = "bingmaps:?cp=";  
    }else{
      protocol = "http://maps.google.com/maps?q=";
    }
    return protocol+lat+","+long;
}