app/views/shared/_chartbeat.html.erb
<% if Rails.env.production? && ENV["CHARTBEAT_HOSTNAME"].present? -%>
<script type="text/javascript">
var _sf_async_config = { uid: <%= ENV["CHARTBEAT_UID"] -%>, domain: '<%= ENV["CHARTBEAT_HOSTNAME"] -%>', useCanonical: true };
(function() {
function loadChartbeat() {
window._sf_endpt = (new Date()).getTime();
var e = document.createElement('script');
e.setAttribute('language', 'javascript');
e.setAttribute('type', 'text/javascript');
e.setAttribute('src','//static.chartbeat.com/js/chartbeat.js');
document.body.appendChild(e);
};
var oldonload = window.onload;
window.onload = (typeof window.onload != 'function') ?
loadChartbeat : function() { oldonload(); loadChartbeat(); };
})();
</script>
<% end -%>