Adding a menu in WinJS.UI.Menu

dataheaderMenu.js

// Within page definition
 // Populate the menu under the title
populateMenu: function (){
  var menu = document.getElementById('headerMenu').winControl;
  for (var i = 0; i < Kippt.lists.meta.total_count; i++) {
    var list = Kippt.lists.objects[i];
    var mc = new WinJS.UI.MenuCommand(null, {
      id: list.id, label: list.title, extraClass: 'caller', onclick: function () {
        nav.navigate("/pages/groupDetail/groupDetail.html", { groupKey:this.id });}});
        menu._addCommand(mc);
        }
 }

headerMenu.html

<!-- Static version -->
<div id="headerMenu" data-win-control="WinJS.UI.Menu">
  <button data-win-control="WinJS.UI.MenuCommand" data-win-options="{id:'collectionMenuItem',label:'Collection'}"></button>
  <button data-win-control="WinJS.UI.MenuCommand" data-win-options="{id:'marketplaceMenuItem',label:'Marketplace'}"></button>
  <button data-win-control="WinJS.UI.MenuCommand" data-win-options="{id:'newsMenuItem',label:'News'}"> </button>
  <hr data-win-control="WinJS.UI.MenuCommand" data-win-options="{id:'separator',type:'separator'}" />
  <button data-win-control="WinJS.UI.MenuCommand" data-win-options="{id:'homeMenuItem',label:'Home'}"></button>
</div>