unselectAllReturns: jQuery object

    
 <button onclick="tree.selectAll()" class="gj-button-md">Select All</button>
 <button onclick="tree.unselectAll()" class="gj-button-md">Unselect All</button>
 <br/>
 <div id="tree" data-source="/Locations/Get"></div>
 <script>
     var tree = $('#tree').tree({
         selectionType: 'multiple'
     });
     tree.on('dataBound', function() {
         tree.expandAll();
     });
 </script>