VisJS Timeline:在时间轴中排序项目

I'm using vis-js timeline library for building a timeline. I need to sort the elements in each group.
Groups are like in example here. I saw that I can do this using the "order option in the item" like here
but I cannot understand how it works.

我试过这样:

var groups = new vis.DataSet([
    {id: 0, content: 'First', value: 1},
    {id: 1, content: 'Third', value: 3},
    {id: 2, content: 'Second', value: 2}
]);

// create a dataset with items

var items = new vis.DataSet([
    {id: 0, group: 0, content: 'item 0', start: new Date(2014, 3, 17), end: new Date(2014, 3, 21)},
    {id: 1, group: 0, content: 'item 1', start: new Date(2014, 3, 19), end: new Date(2014, 3, 20)},
    {id: 2, group: 1, content: 'item 2', start: new Date(2014, 3, 16), end: new Date(2014, 3, 24)},
    {id: 3, group: 1, content: 'item 3', start: new Date(2014, 3, 23), end: new Date(2014, 3, 24)},
    {id: 4, group: 1, content: 'item 4', start: new Date(2014, 3, 22), end: new Date(2014, 3, 26)},
    {id: 5, group: 2, content: 'item 5', start: new Date(2014, 3, 24), end: new Date(2014, 3, 27)}
  ]);

  // create visualization
  var container = document.getElementById('visualization');
  var options = {

    editable: true
  };

var timeline = new vis.Timeline(container);
timeline.setOptions(options);
timeline.setGroups(groups);
var temp = items.get({
    order:function(a,b){
        return b.id-a.id;
        if(a.id > b.id)
            return -1;
        if(a.id < b.id)
            return 1;

        return 0;
    },
});

  timeline.setItems(temp);

变量 temp 包含一个已排序的数组，但在创建时间线时 - 在第三组中排序的项目如下:item3、item2、item4.
但它们必须像 item2、item3、item4 一样排序.

var options = {
  order: function(a,b){
    return b.id-a.id;
  },
  editable: true
};

timeline.setOptions({
  order: function(a,b){
    return b.id-a.id;
  },
});