SOURCE

function objectAverage(arr, ignore) {
  const helper = new Map()
  const res = {}
  function handleDataToMap(data, parent) {
    // 需要忽略的key
    if (ignore && parent.length && parent[parent.length - 1] === ignore) {
      return
    }
    const dataType = typeof data
    if (data !== null && dataType === 'object') {
      for (const key in data) {
        if (Object.hasOwnProperty.call(data, key)) {
          handleDataToMap(data[key], [...parent, key]);
        }
      }
    } else if (dataType === 'number') {
      const key = parent.join('|')
      let val = helper.get(key)
      if (!val) {
        val = {
          value: 0,
          count: 0,
        }
        helper.set(key, val)
      }
      val.value += data
      val.count++
    }
  }

  if (!arr?.length) {
    return null
  }

  for (const item of arr) {
    handleDataToMap(item, [])
  }

  for (const [k, v] of helper.entries()) {
    setIn(res, k.split('|'), parseFloat((v.value / v.count).toFixed(2)))
  }

  return res
}

function setIn(obj, keys, value) {
  const len = keys.length
  if (len === 0) {
    return
  }
  const key = keys.shift()

  if (len === 1) {
    obj[key] = value
  } else {
    if (!Object.prototype.hasOwnProperty.call(obj, key)) {
      obj[key] = {}
    }
    setIn(obj[key], keys, value)
  }
}

const testListWithNestedDicts = [
  {
    "studentId": 1,
    "age": 7,
    "height": 2,
    "weight": 3,
    "scores": {
      "spanish": 80,
      "mathematics": 90,
      "english": 100,
      "pe": {
        "run": 85,
        "jump": 95
      }
    }
  },
  {
    "studentId": 2,
    "age": 8,
    "height": 4,
    "weight": 6,
    "scores": {
      "spanish": 90,
      "mathematics": 90,
      "english": 80,
      "pe": {
        "run": 90,
        "jump": 90
      }
    }
  },
  {
    "studentId": 3,
    "age": 7,
    "height": 3,
    "weight": 6,
    "scores": {
      "spanish": 86,
      "mathematics": 90,
      "english": 75,
      "pe": {
        "run": 65,
        "jump": 90
      }
    }
  }
]

console.log(objectAverage(testListWithNestedDicts, 'studentId'))