text: // https://github.com/ghiculescu/jekyll-table-of-contents
  (function($){
    $.fn.toc = function(options) {
      var defaults = {
        noBackToTopLinks: false,
        title: '<i>Jump to...</i>',
        minimumHeaders: 3,
        headers: 'h1, h2, h3, h4, h5, h6',
        listType: 'ol', // values: [ol|ul]
        showEffect: 'show', // values: [show|slideDown|fadeIn|none]
        showSpeed: 'slow' // set to 0 to deactivate effect
      },
      settings = $.extend(defaults, options);
  
      var headers = $(settings.headers).filter(function() {
        // get all headers with an ID
        var previousSiblingName = $(this).prev().attr( "name" );
        if (!this.id && previousSiblingName) {
          this.id = $(this).attr( "id", previousSiblingName.replace(/\./g, "-") );
        }
        return this.id;
      }), output = $(this);
      if (!headers.length || headers.length < settings.minimumHeaders || !output.length) {
        return;
      }
  
      if (0 === settings.showSpeed) {
        settings.showEffect = 'none';
      }
  
      var render = {
        show: function() { output.hide().html(html).show(settings.showSpeed); },
        slideDown: function() { output.hide().html(html).slideDown(settings.showSpeed); },
        fadeIn: function() { output.hide().html(html).fadeIn(settings.showSpeed); },
        none: function() { output.html(html); }
      };
  
      var get_level = function(ele) { return parseInt(ele.nodeName.replace("H", ""), 10); }
      var highest_level = headers.map(function(_, ele) { return get_level(ele); }).get().sort()[0];
      var return_to_top = '<i class="icon-arrow-up back-to-top"> </i>';
  
      var level = get_level(headers[0]),
        this_level,
        html = settings.title + " <"+settings.listType+">";
      headers.on('click', function() {
        if (!settings.noBackToTopLinks) {
          window.location.hash = this.id;
        }
      })
      .addClass('clickable-header')
      .each(function(_, header) {
        this_level = get_level(header);
        if (!settings.noBackToTopLinks && this_level === highest_level) {
          $(header).addClass('top-level-header').after(return_to_top);
        }
        if (this_level === level) // same level as before; same indenting
          html += "<li><a href='#" + header.id + "'>" + header.innerHTML + "</a>";
        else if (this_level <= level){ // higher level than before; end parent ol
          for(i = this_level; i < level; i++) {
            html += "</li></"+settings.listType+">"
          }
          html += "<li><a href='#" + header.id + "'>" + header.innerHTML + "</a>";
        }
        else if (this_level > level) { // lower level than before; expand the previous to contain a ol
          for(i = this_level; i > level; i--) {
            html += "<"+settings.listType+"><li>"
          }
          html += "<a href='#" + header.id + "'>" + header.innerHTML + "</a>";
        }
        level = this_level; // update for the next one
      });
      html += "</"+settings.listType+">";
      if (!settings.noBackToTopLinks) {
        $(document).on('click', '.back-to-top', function() {
          $(window).scrollTop(0);
          window.location.hash = '';
        });
      }
  
      render[settings.showEffect]();
    };
  })(jQuery);
  