function trackSharingEvents(event) {
  if (event.type == 'addthis.menu.share') {
    $.post('/social/activities', { title: document.title, service: event.data.service, url: window.location.href });
  }
}

$(document).ready(function() {
  if (typeof addthis != "undefined") {
    addthis.addEventListener('addthis.menu.share', trackSharingEvents);
  }
});