Toggling sidebar v2 in Leaflet

HTML

<script src="http://cdn.leafletjs.com/leaflet-0.7.5/leaflet.js"></script>
<link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet-0.7.5/leaflet.css">
<script src="//rawgit.com/Turbo87/sidebar-v2/master/js/leaflet-sidebar.min.js"></script>
<link rel="stylesheet" href="//rawgit.com/Turbo87/sidebar-v2/master/css/leaflet-sidebar.min.css">
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.1.0/css/font-awesome.min.css">
<div id="sidebar" class="sidebar sidebar-left collapsed">
  <!-- Nav tabs -->
  <div class="sidebar-tabs">
    <ul role="tablist">
      <li class=""><a href="#home" role="tab"><i class="fa fa-bars"></i></a></li>
      <li><a href="#profile" role="tab"><i class="fa fa-user"></i></a></li>
      <li class="disabled"><a href="#messages" role="tab"><i class="fa fa-envelope"></i></a></li>
    </ul>

    <ul role="tablist">
      <li><a href="#settings" role="tab"><i class="fa fa-gear"></i></a></li>
    </ul>
  </div>

  <!-- Tab panes -->
  <div class="sidebar-content">
    <div class="sidebar-pane active" id="home">
      <h1 class="sidebar-header">
                    sidebar-v2
                    <span class="sidebar-close"><i class="fa fa-caret-left"></i></span>
                </h1>
      <p>A responsive sidebar for mapping libraries like <a href="http://leafletjs.com/">Leaflet</a> or <a href="http://openlayers.org/">OpenLayers</a>.</p>

      <p class="lorem">Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea
        takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores
        et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus...

CSS

#map {
  height: 400px;
}

#sidebar {
  height: 380px;
}

JavaScript

var map = L.map('map').setView([34.05, -118.25], 10);
ATTR = '&copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, ' +
  '<a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a> | ' +
  '&copy; <a href="http://cartodb.com/attributions">CartoDB</a>';
CDB_URL = 'http://{s}.basemaps.cartocdn.com/light_all/{z}/{x}/{y}.png';
L.tileLayer(CDB_URL, {
  attribution: ATTR
}).addTo(map);

var sidebar = L.control.sidebar('sidebar').addTo(map);

var sidebarDiv = document.getElementById('sidebar');

toggleSidebar = function() {
  if (hasClass(sidebarDiv,'collapsed')) {
    sidebar.open();
  } else {
    sidebar.close();
  }
}

function hasClass(element, cls) {
  return (' ' + element.className + ' ').indexOf(' ' + cls + ' ') > -1;
}