(function (win, doc) {
const testButton = doc.createElement('button');
testButton.setAttribute('type','share');
if (testButton.type != 'share') {
  win.addEventListener('click', function(ev) {
    ev = ev || win.event;
    let target = ev.target;
    let button = target.closest('button[type="share"]');
    if (button) {
      const title = doc.querySelector('title').innerText;
      const url = win.location.href;
      if (navigator.share) {
        navigator.share({ title: title, url: url });
      } else {
        win.location.href='mailto:?subject='+title+'&body='+url;
      }
    }
  });
}
}(this, this.document));