text:   // check operating system function
  function checkOS() {
      let os = "unknown"; 
      let isWin = false;
      let isMac = false;
      let isUnix = false;
      let isLinux = false;
      let isWinMob = false;
      let isAndroid = false;
      let isiOS = false;
  
      let userAgent = navigator.userAgent || navigator.vendor || window.opera;
      if (userAgent.indexOf("Win") != -1) {
          os = "Windows OS";
          isWin = true ;
      }
          
      if (userAgent.indexOf("Mac") != -1) {
          os = "Mac";
          isMac = true;
      }
        
      if (userAgent.indexOf("X11") != -1) {
          os = "UNIX OS";
          isUnix = true;
      }
          
      if (userAgent.indexOf("Linux") != -1) {
          os = "Linux OS";
          isLinux = true; 
      }
      
      if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|ipad|iris|kindle|Android|Silk|lge |maemo|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(navigator.userAgent) 
      || /1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(navigator.userAgent.substr(0,4))) {
          
          if (/windows phone/i.test(userAgent)) {
              os ="Windows Mobile";
              isWinMob = true;
          }
           
          if (/android/i.test(userAgent)) {
              os = "Android";
              isAndroid = true;
          } 
             
          if (/iPad|iPhone|iPod/.test(userAgent) && !window.MSStream) {
              os = "iOS";
              isiOS = true;
          }
      }
      
      return [os,isWin,isMac,isUnix,isLinux,isWinMob,isAndroid,isiOS];
    }
  
    // check browser function
    function checkBrowser() {
      let browser = "unknown";
      let isChrome = false;
      let isFirefox = false;
      let isIE = false;
      let isEdge = false;
      let isSafari = false;
      let isOpera = false;
      let isYandex = false;
  
      if (navigator.userAgent.indexOf("Chrome") != -1 ) {
          browser = "Google Chrome";
          isChrome = true;
        }
        else if (navigator.userAgent.indexOf("Firefox") != -1 ) {
          browser = "Mozilla Firefox";
          isFirefox = true;
        }
        else if (navigator.userAgent.indexOf("MSIE") != -1 ) {
          browser = "Internet Explorer";
          isIE = true;
        }
        else if (navigator.userAgent.indexOf("Edge") != -1 ) {
          browser = "Edge";
          isEdge = true;
        }
        else if (navigator.userAgent.indexOf("Safari") != -1 ) {
          browser = "Safari";
          isSafari = true;
        }
        else if (navigator.userAgent.indexOf("Opera") != -1 ) {
          browser = "Opera";
          isOpera = true;
        }
        else if (navigator.userAgent.indexOf("Opera") != -1 ) {
          browser = "Yandex Browser";
          isYandex = true;
        }
  
        return [browser,isChrome,isFirefox,isIE,isEdge,isSafari,isOpera,isYandex];
    }
  
    // check device config function
    function checkDeviceConfig() {
      let deviceConfig = [];
      let isCookieEnabled = false;
      let isOnLine = false;
      let knownLangs = "unknown";
      let prefLang = "unknown";
      let isJavaEnabled = false;
  
      if (navigator.cookieEnabled) {
        deviceConfig = deviceConfig => deviceConfig.concat({'isCookieEnabled':true});
        isCookieEnabled = true;
      }
      if (navigator.onLine) {
        deviceConfig = deviceConfig => deviceConfig.concat({'isOnLine':true});
        isOnline = true;
      }
      if (navigator.languages) {
        deviceConfig = deviceConfig => deviceConfig.concat({'knownLangs':navigator.languages})
        knownLangs = navigator.languages;
      }
      if (navigator.language) {
        deviceConfig = deviceConfig => deviceConfig.concat({'prefLang':navigator.language})
        prefLang = navigator.language
      }
      if(navigator.javaEnabled()) {
        deviceConfig = deviceConfig => deviceConfig.concat({'isJavaEnabled':true})
        isJavaEnabled = true;
      }
  
      return [deviceConfig,isCookieEnabled,isOnLine,knownLangs,prefLang,isJavaEnabled]
    }
  