具有ES6解构的反应js中的setState

Question

我有这个设置状态::

的反应代码

onMoveUp={(ids: SelectedIdMap) => {
              this.setState({
                xyz: {
                  ...this.state.xyz,
                  [tt]: [
                    ...this.state.xyz[tt].filter(a => (a.id in ids)),
                    ...this.state.xyz[tt].filter(a => !(a.id in ids)),
                  ],
                },
              });
            }}

此代码将传递的数组元素（ids）的索引更改为数组顶部。

目前的状态是这样的::

{"51f6c052-b218-45ce-b3db-c9b95249e03a":[{"id":"11553dc4-d194-476c-9e05-aaac28ea3e76","prediction":"India–Japan relations","confidence":1},{"id":"3f76ce1d-a821-4418-a332-3285176ae456","prediction":"Japan Democratic Party (1954) politicians","confidence":1},{"id":"031d3913-984a-4af7-aaa3-73e23c206ff1","prediction":"Japan–Taiwan relations","confidence":1}]}

我无法理解 [tt] 在此代码中的含义＆amp;如何更新。

ids = 11553dc4-d194-476c-9e05-aaac28ea3e76 in the parameter.

这是一个愚蠢的问题，但请帮助我理解。