js 数组集合过滤取值

Question

原始数据

(6) [{…}, {…}, {…}, {…}, {…}, {…}]
  0:
  assId: 1
  categoryList: []

> disableLeverList: (10) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  id: 1
  level: []
  reasonList: (13) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  typeCode: "1"
  typeName: "1"
  typeValue: "1"
  __proto__: Object
  1:
  assId: 2
  categoryList: []
> disableLeverList: (10) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  id: 2
  level: []
  reasonList: (15) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  typeCode: "2"
  typeName: "2"
  typeValue: "1"
  __proto__: Object
  2:
  assId: 3
  categoryList: []
> disableLeverList: (10) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  id: 3
  level: []
  reasonList: (15) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  typeCode: "3"
  typeName: "3"
  typeValue: "1"
  __proto__: Object

想得到

(6) [{…}, {…}, {…}, {…}, {…}, {…}]
  0:
  assId: 1
  categoryList: []
> disableLeverList: (4) [{…}, {…}, {…}, {…}]
  id: 1
  level: []
  reasonList: (13) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  typeCode: "1"
  typeName: "1"
  typeValue: "1"
  __proto__: Object
  1:
  assId: 2
  categoryList: []

> disableLeverList: (4) [{…}, {…}, {…}]
  id: 2
  level: []
  reasonList: (15) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  typeCode: "2"
  typeName: "2"
  typeValue: "1"
  __proto__: Object
  2:
  assId: 3
  categoryList: []
> disableLeverList: (4) [{…}, {…}, {…}, {…}]
  id: 3
  level: []
  reasonList: (15) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
  typeCode: "3"
  typeName: "3"
  typeValue: "1"
  __proto__: Object

我想取最大数组（length为6）下的disableLeverList数组，需要拿取disableLeverList数组的前4个值，后面的6个值过滤掉，然后不影响数组数组结构和最大数组（length为6）

Answer 1

function transform(arr){
    return arr.map(item => {
        item.disableLeverList = item.disableLeverList.slice(0, 4);
        return item;
    })
}

Answer 2

arr[arr.length -1 ].disableLeverList.slice(0,4)

//楼主改过题目，答案无效