var url = 'https://wiki.teamfortress.com/wiki/Main_Page';
$.getJSON('https://api.gosquared.com/now/v3/pages?api_key=demo&site_token=GSN-106863-S&href=' + encodeURIComponent(url), function(data) {
  $('#online-now').addClass('visible').find('.visitors').text(data.visitors);
});
<p id="online-now"><span class="visitors">0</span> people are currently viewing the Team Fortress 2 Homepage.</p>
#online-now {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  /* start with the text hidden */
  opacity: 0;
  /* add a transition so it'll fade in nicely */
  transition: opacity 0.2s ease-out;
}

#online-now.visible {
  opacity: 1;
}