content/_includes/footer_scripts.html

<script>

    function addCollapsed(el) {
        el.classList.add('collapsed');
    }

    function toggleCollapsed(ev) {
        ev.target.parentNode.classList.toggle('collapsed');
        ev.preventDefault();
    }

    function addClickEvent(el) {
        console.log(el);
        el.addEventListener('click', toggleCollapsed);
    }

    document.querySelectorAll('.sidebar-node').forEach(addCollapsed);
    document.querySelectorAll('.sidebar-node > a').forEach(addClickEvent);

    // preserve expand/collapse across page navigation
    var path = document.location.pathname;
    if (path.indexOf('/1.8') == 0) {
        var el = document.getElementById("#v1-8");
        el.classList.toggle("collapsed");
        if (path.indexOf('/1.8/cookbook') == 0) {
            el = document.getElementById('v1-8-cookbook');
            el.classList.remove('collapsed');
        }
    } else {
        var el = document.getElementById("v2-0");
        console.log(el);
        el.classList.remove("collapsed");
        if (path.indexOf('/2.0/cookbook') == 0) {
            el = document.getElementById('#v2-0-cookbook');
            el.classList.remove('collapsed');
        }
    }
</script>