tree.js

$('.sortable').nestedSortable({
    forcePlaceholderSize: true,
    handle: 'div',
    helper: 'clone',
    items: 'li',
    opacity: .6,
    placeholder: 'placeholder',
    revert: 250,
    tabSize: 25,
    tolerance: 'pointer',
    toleranceElement: '> div',
    maxLevels: 4,
    isTree: true,
    expandOnHover: 700,
    startCollapsed: false,
    relocate: function(data){
      data
      array = $('ol.sortable').nestedSortable('toArray', {startDepthCount: 0});
      $.ajax({
        url: "/backend/familles/change_order",
        type: "POST",
        data: {sort_array:  JSON.stringify(array)}
      });
    }
 });