app/views/shared/_facebook_connect.html.erb
<%- if ENV["FACEBOOK_APP_ID"].present? -%>
<script>
window.fbAsyncInit = function () {
FB.init({
appId: '<%= ENV["FACEBOOK_APP_ID"] -%>',
status: true,
cookie: true,
logging: false,
xfbml: true,
channelUrl: '<%= channel_url %>'
});
};
(function(d, s, id) {
var js, fjs = d.getElementsByTagName(s)[0];
if (d.getElementById(id)) return;
js = d.createElement(s); js.id = id;
js.src = "//connect.facebook.net/en_US/all.js"; // adding parameters calls FB.init
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));
</script>
<%- end %>