javascript - 有没有一种简单的方法可以循环遍历一个对象，该对象的值是对象数组，以从这些对象的值生成列表

Question

我有一个 JSON 对象，正在导入到类似于以下内容的 React 页面中:

const obj1 = {
  "January": [
    {
      "Id": 1,
      "FileName": "some file",
      "Format": "Excel (.xlsx)",
      "Category": "some category 1",
      "Start": "01/01/2019",
      "End": "12/31/2019",
      "Created": "01/09/2019"
    },
    {
      "Id": 2,
      "FileName": "some big file",
      "Format": "Excel (.xlsx)",
      "Category": "some category 2",
      "Start": "01/01/2018",
      "End": "12/31/2018",
      "Created": "01/09/2019"
    }
  ],
  "February": [
    {
      "Id": 3,
      "FileName": "some small file",
      "Format": "PDF (.pdf)",
      "Category": "some category 3",
      "Start": "01/01/2018",
      "End": "12/31/2018",
      "Created": "01/09/2019"
    },
    {
      "Id": 4,
      "FileName": "some other file",
      "Format": "Excel (.xlsx)",
      "Category": "some category 4",
      "Start": "01/01/2018",
      "End": "12/31/2018",
      "Created": "01/09/2018"
    }
  ],
  "March": [
    {
      "Id": 55,
      "FileName": "some file again",
      "Format": "Excel (.xlsx)",
      "Category": "some category 5",
      "Start": "01/01/2017",
      "End": "12/31/2017",
      "Created": "01/09/2017"
    }
  ]
};

我想循环遍历上述对象，并​​使用每个唯一类别动态填充选择下拉元素的选项。

选择看起来像这样:

<select className="selectpicker" data-width="fit" value="All" onChange={this.addSomeOptions}>
  <option >Category 1</option>
  <option >Category 2</option>
  <option >Category 3</option>
</select>

有什么好的方法吗？谢谢!

Answer 1

您可以尝试展平数组并通过它进行映射以提取值

Object.values(obj1).flat().map((a)=> a.Category)

如果数组始终是一维，则可以省略 flat()

结果:

["some category 1", "some category 2", "some category 3", "some category 4", "some category 5"]