JSFiddle - React, Tailwind, and code Playground

JavaScript

var testImg = new Image();

testImg.onload = function() {
  alert('facebook REACHABLE');
};

testImg.onerror = function() {
  alert('facebook UNREACHABLE');
};

testImg.src = '//www.facebook.com/images/fb_logo_small.png?' + new Date().getTime();