website/_includes/i18n-as-script.html

{% comment %}
  get the current translations from Jekyll, to be used in scripts
{% endcomment }%}
<script>
  var i18n_default = {{ site.data.i18n.en.script | jsonify }};
  window.i18n = {{ i18n.script | jsonify }} || {};
  window.i18n.url_base = {{ url_base | jsonify }};
  window.i18n.active_language = {{ vars_active_language.tag | jsonify }};
  
  // give defaults
  function copyDefaults(from, to) {
    for (var key in from) {
      if (from[key] !== null && typeof from[key] === 'object') {
        copyDefaults(from[key], to[key] || (to[key] = {}));
        continue;
      }
      if (to.hasOwnProperty(key) === false || to[key] === null) {
        to[key] = from[key];
      }
    }
  }

  copyDefaults(i18n_default, window.i18n);
</script>