Js recursively finds the last level array and returns it as a new array.

     [
{
  "clockInState": 0,
  "sectionNum": "1",
  "courseBegin": "2019-02-09 00:00:00.0",
  "teacherName": "",
  "drillID": 0,
  "childList": [
    {
      "clockInState": 0,
      "sectionNum": "1",
      "courseBegin": "2019-02-09 00:00",
      "teacherName": "",
      "drillID": 0,
      "childList": [
        {
          "clockInState": 0,
          "sectionNum": "1",
          "courseBegin": "2019-02-09 00:00",
          "teacherName": "",
          "drillID": 0,
          "sectionId": 145,
          "sectionLevel": "3",
          "parentId": 131,
          "content": "",
          "sectionName": "",
          "courseDrillId": 10,
          "userSectionStats": 0,
          "courseCover": "courseCover/courseCover1547003167675.png"
        }
      ],
      "sectionId": 131,
      "sectionLevel": "2",
      "parentId": 55,
      "content": "day1",
      "sectionName": "day1",
      "courseDrillId": 10,
      "userSectionStats": 1,
      "courseCover": "courseCover/courseCover1547003167675.png"
    }
  ],
  "sectionId": 55,
  "sectionLevel": "1",
  "parentId": 0,
  "content": "",
  "sectionName": "",
  "courseDrillId": 10,
  "userSectionStats": 1,
  "courseCover": "courseCover/courseCover1547003167675.png"
},
{
  "clockInState": 0,
  "sectionNum": "2",
  "courseBegin": "2019-02-09 00:00:00.0",
  "teacherName": "",
  "drillID": 0,
  "childList": [
    {
      "clockInState": 0,
      "sectionNum": "14",
      "courseBegin": "2019-02-22 00:00",
      "teacherName": "",
      "drillID": 0,
      "childList": [
        {
          "sectionName": "",
          "clockInState": 0,
          "sectionNum": "1",
          "courseDrillId": 10,
          "courseBegin": "2019-02-22 00:00",
          "teacherName": "",
          "drillID": 0,
          "userSectionStats": 0,
          "sectionId": 210,
          "sectionLevel": "3",
          "courseCover": "courseCover/courseCover1547003167675.png",
          "parentId": 209
        }
      ],
      "sectionId": 209,
      "sectionLevel": "2",
      "parentId": 207,
      "sectionName": "day1",
      "courseDrillId": 10,
      "userSectionStats": 1,
      "courseCover": "courseCover/courseCover1547003167675.png"
    },
    {
      "clockInState": 0,
      "sectionNum": "15",
      "courseBegin": "2019-02-23 00:00",
      "teacherName": "",
      "drillID": 0,
      "childList": [
        {
          "sectionName": "",
          "clockInState": 0,
          "sectionNum": "1",
          "courseDrillId": 10,
          "courseBegin": "2019-02-23 00:00",
          "teacherName": "",
          "drillID": 0,
          "userSectionStats": 0,
          "sectionId": 402,
          "sectionLevel": "3",
          "courseCover": "courseCover/courseCover1547003167675.png",
          "parentId": 236
        }
      ],
      "sectionId": 236,
      "sectionLevel": "2",
      "parentId": 207,
      "sectionName": "day2",
      "courseDrillId": 10,
      "userSectionStats": 1,
      "courseCover": "courseCover/courseCover1547003167675.png"
    }
  ],
  "sectionId": 207,
  "sectionLevel": "1",
  "parentId": 0,
  "content": "undefined",
  "sectionName": "",
  "courseDrillId": 10,
  "userSectionStats": 1,
  "courseCover": "courseCover/courseCover1547003167675.png"
}
]

find the array of each last level childList as above, and return it as a new array.

the environmental background of the problems and what methods you have tried

related codes

/ / Please paste the code text below (do not replace the code with pictures)

what result do you expect? What is the error message actually seen?

/** * * level maxLevel * * maxLevel maxLevel */ function find(data) { var maxLevel = 0, coll = []; for (let i = 0; i < data.length; iPP) { let ret = []; maxLevel = 0; walk(data[i], ret, 1); coll.push(ret.filter(node => node.level >= maxLevel)); } /** * * @param {Object} node * @param {Array} ret * @param {number} level level */ function walk(node, ret, level) { if ((!node.childList || node.childList.length === 0 ) && level >= maxLevel) { node.level = level; ret.push(node); maxLevel = level; return; } for (let w of node.childList) { walk(w, ret, level + 1); } } } find(data);

const result = []; data.forEach(item => {// const loop = data => { let child = data.childList; if(child){// for(let i = 0; i < child.length; iPP){ loop(child[i]); } } else { result.push(data); } } loop(item); }) return result;