Google Connectivity Check

GoogleRecaptchaConnectivity.js

var connectivityFirstCheck = true;
var connectivityTestPassed;
// https://github.com/SukkaW/DisqusJS/blob/master/src/disqus.js#L235
const connectivityCheck = () => {
  connectivityFirstCheck = false;
  const img = new Image;

  const timeout = setTimeout(() => {
    img.onerror = img.onload = null;
    connectivityTestPassed = false;
    connectivityCallback();
  },
  3000);

  img.onerror = () => {
    clearTimeout(timeout);
    connectivityTestPassed = false;
    connectivityCallback();
  }

  img.onload = () => {
    clearTimeout(timeout);
    connectivityTestPassed = true;
    connectivityCallback();
  }

  img.src = "https://www.google.com/images/hpp/icon-privacy-shield-rgb-120dp.png";

  var recaptchaURL;
  var recaptchaHost = "https://www.google.com";
  var recaptchaHostMirror = "https://www.recaptcha.net";
  var recaptchaPath = "/recaptcha/api.js?onload=anr_onloadCallback&render=explicit";

  const scriptInjecting = () => {
    var script = document.createElement('script');
    script.type = "text/javascript";
    script.src = recaptchaURL;
    script.async=true;
    script.defer=true;
    document.getElementsByTagName('head')[0].appendChild(script);
  }

  const connectivityCallback = () => {
    if(connectivityTestPassed == true){
      recaptchaURL = recaptchaHost + recaptchaPath;
      scriptInjecting();
    } else {
      recaptchaURL = recaptchaHostMirror + recaptchaPath;
      scriptInjecting();
    }
  }
}

// Run the check.
$(".comment-form-comment>textarea").focus(function(){
  if (connectivityFirstCheck == true) {
    connectivityCheck();
  }
});