a very simple table of contents.

toc.js

jQuery(function ($) {

    var $headings = $('h1, h2, h3', '#content');
    var $h2 = $('h2', '#content');
    // Only if two or more level 2 headings.
    // and if content is larger then window.
    if (($h2.length > 1 || $headings.length > 6) && $('#content').height() > $(window).height() * 1.25) {
        var $nav = $('<nav>').attr('id', 'toc');
        $nav.insertAfter('#sidebar');

        (function ($nav, $headings) {
            var slugify = function (str) {
                str = str.replace(/^\s+|\s+$/g, ''); // trim
                str = str.toLowerCase();

                // remove accents, swap ñ for n, etc
                var from = "ãàáäâẽèéëêìíïîõòóöôùúüûñç·/_,:;";
                var to = "aaaaaeeeeeiiiiooooouuuunc------";
                for (var i = 0, l = from.length; i < l; i++) {
                    str = str.replace(new RegExp(from.charAt(i), 'g'), to.charAt(i));
                }

                str = str.replace(/[^a-z0-9 -]/g, '') // remove invalid chars
                    .replace(/\s+/g, '-') // collapse whitespace and replace by -
                    .replace(/-+/g, '-') // collapse dashes
                    .replace(/^-+|-+$/, ''); // trim

                return str;
            };
            $headings.each(function (i) {
                var $heading = $(this);
                var text = $heading.text();
                var level = $heading.prop("tagName").replace(/[^0-9]/, '');
                //if (level == 1) {
                //	$nav.append('<strong>Op deze pagina: ' + text + '</strong>');
                //	return;
                //}
                var slug = $heading.attr('id');
                if (!slug || slug.replace(/^\s+|\s+$/g, '') == '') {
                    var slug = 'toc' + (i + 1) + '-' + slugify(text);
                    $heading.attr('id', slug);
                }
                if (level < 3) {
                    $heading.prepend($('<a>&uarr; Terug naar boven</a>').addClass('toc-up-arrow').attr('href', '#' + $nav.attr('id')));
                }

                $('<a> ').addClass('level' + level).attr('href', '#' + slug).text(text).appendTo($nav);
            });
        })($nav, $headings);
});