Javascript - Couting all nested objects of JSON

Question

Suppose I have the following 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": []
                    }
                  ]
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}

My question is: How could I count each of the childs and append this number into a property of each object?

Example:

• The "C" object has 2 objects inside and on subobjects, "D" and "E".
• The "W" object has 3 objects inside and on subobjects, "X", "Y" and "Z".
• The "V" ovject has (here is the trick) 4 objects inside and on subobjects, The "W" object itself and all of its childs (the 3 ones aforementioned).

Regarding this, the "C" object should have a property, let's name it "allBelow", containing the number 2. The "W" object containing 3, and the "V" object containing 4. And so on, for each object.

I wonder that some recursive function could do this job but I'm not achieving it.

Could you please help me?

Bests,

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);