Javascript - 计算 JSON 的所有嵌套对象

Question

假设我有以下 JSON：

{
  "id": "foo",
  "list": [
    {
      "id": "A",
      "list": [
        {
          "id": "B",
          "list": [
            {
              "id": "C",
              "list": [
                {
                  "id": "D",
                  "list": []
                },
                {
                  "id": "E",
                  "list": []
                }
              ]
            },
            {
              "id": "F",
              "list": []
            },
            {
              "id": "G",
              "list": [
                {
                  "id": "H",
                  "list": []
                },
                {
                  "id": "I",
                  "list": []
                },
                {
                  "id": "J",
                  "list": []
                }
              ]
            }
          ]
        },
        {
          "id": "K",
          "list": []
        }
      ]
    },
    {
      "id": "L",
      "list": [
        {
          "id": "M",
          "list": []
        }
      ]
    },
    {
      "id": "N",
      "list": []
    },
    {
      "id": "O",
      "list": [
        {
          "id": "P",
          "list": [
            {
              "id": "Q",
              "list": []
            },
            {
              "id": "R",
              "list": []
            },
            {
              "id": "S",
              "list": []
            },
            {
              "id": "T",
              "list": [
                {
                  "id": "U",
                  "list": []
                }
              ]
            },
            {
              "id": "V",
              "list": [
                {
                  "id": "W",
                  "list": [
                    {
                      "id": "X",
                      "list": []
                    },
                    {
                      "id": "Y",
                      "list": []
                    },
                    {
                      "id": "Z",
                      "list": []
                    }
                  ]
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}

我的问题是：我如何计算每个孩子并将这个数字附加到每个对象的属性中？

例子：

• “C”对象在子对象“D”和“E”内部和之上有 2 个对象。
• “W”对象在子对象内部和之上有 3 个对象，“X”、“Y”和“Z”。
• “V”对象有（这是诀窍）在子对象内部和子对象上的 4 个对象，“W”对象本身及其所有子对象（3前面提到的）。

关于这个，“C”对象应该有一个属性，我们将其命名为“allBelow”，包含数字2。“W”对象包含3，“V”对象包含4。以此类推，对于每个对象。

我想知道一些递归函数可以完成这项工作，但我没有实现。

你能帮帮我吗？

最佳，

Answer 1

var myObj = {"id":"foo","list":[{"id":"A","list":[{"id":"B","list":[{"id":"C","list":[{"id":"D","list":[]},{"id":"E","list":[]}]},{"id":"F","list":[]},{"id":"G","list":[{"id":"H","list":[]},{"id":"I","list":[]},{"id":"J","list":[]}]}]},{"id":"K","list":[]}]},{"id":"L","list":[{"id":"M","list":[]}]},{"id":"N","list":[]},{"id":"O","list":[{"id":"P","list":[{"id":"Q","list":[]},{"id":"R","list":[]},{"id":"S","list":[]},{"id":"T","list":[{"id":"U","list":[]}]},{"id":"V","list":[{"id":"W","list":[{"id":"X","list":[]},{"id":"Y","list":[]},{"id":"Z","list":[]}]}]}]}]}]};

function count(obj) {
  var c = obj.list.length;
  c += obj.list.reduce((a, e) => a + count(e), 0);
  obj.count = c; // assign the count after counting the subobjects.
  return c; // return the count to be used by parent objects
}

count(myObj);

console.log(myObj);

Answer 2

递归函数是个好主意。试试这个：

var data = {"id":"foo","list":[{"id":"A","list":[{"id":"B","list":[{"id":"C","list":[{"id":"D","list":[]},{"id":"E","list":[]}]},{"id":"F","list":[]},{"id":"G","list":[{"id":"H","list":[]},{"id":"I","list":[]},{"id":"J","list":[]}]}]},{"id":"K","list":[]}]},{"id":"L","list":[{"id":"M","list":[]}]},{"id":"N","list":[]},{"id":"O","list":[{"id":"P","list":[{"id":"Q","list":[]},{"id":"R","list":[]},{"id":"S","list":[]},{"id":"T","list":[{"id":"U","list":[]}]},{"id":"V","list":[{"id":"W","list":[{"id":"X","list":[]},{"id":"Y","list":[]},{"id":"Z","list":[]}]}]}]}]}]};

function addCount(node) {
  node.count = 0;
  for (var i = 0; i < node.list.length; i++) {
    var child = node.list[i];
    addCount(child);
    node.count += child.count + 1;
  }
}

addCount(data);
console.log(data)

它首先在每个子节点上调用自己。然后它将每个孩子添加到计数中，即 1 + 孙辈（或孙辈或更多）的数量。

Answer 3

深度优先搜索应该可行，我在想这样的事情（未经测试的代码）：

function DFS(tree){
    var currentCount = tree.list.length;
    for(var i=0;i<count;i++){
        currentCount += DFS(tree.list[i]);
    }
    tree["count"] = currentCount;
    return currentCount;
}

Answer 4

你可以做一个简单的 DFS：

function appendNumChildren(currentNode) {  
  const totalChildren = currentNode.list.reduce((acc, node) => {
    return acc + appendNumChildren(node);
  }, 0)

  currentNode.allBelow = totalChildren;

  return totalChildren + 1;
}

appendNumChildren(json);

https://jsbin.com/qekabatuwi/edit?js,console