I didn't write this code

gistfile1.js

AboutContent = {
    defaultSection: "branching-and-merging",
    init: function() {
        if ($("body#about").length === 0) return;
        AboutContent.observeNav(),
        AboutContent.observePopState(),
        AboutContent.showSection(AboutContent.getSection())
    },
    observePopState: function() {
        if (window.history && window.history.pushState) return $(window).bind("popstate",
        function(a) {
            var b;
            initialPop = !popped && location.href === initialURL,
            popped = !0;
            if (initialPop) return;
            return b = AboutContent.getSection(),
            AboutContent.showSection(b)
        })
    },
    getSection: function(a) {
        var b;
        b = location.href.substring(location.href.lastIndexOf("/") + 1);
        if (b.length === 0 || b == "about") b = AboutContent.defaultSection;
        return b
    },
    showSection: function(a) {
        a == "about" && (a = AboutContent.defaultSection),
        $("ol#about-nav a").removeClass("current"),
        $("ol#about-nav a#nav-" + a).addClass("current"),
        $("section").hide(0,
        function() {
            $("section#" + a).show()
        })
    },
    observeNav: function() {
        $("ol#about-nav a, .bottom-nav a").click(function(a) {
            a.preventDefault();
            var b = $(this).attr("data-section-id");
            window.history && window.history.pushState && history.pushState(null, $(this).html(), "/about/" + b),
            AboutContent.showSection(b)
        })
    }
}