how to count appearance of a given key in nested object-CodePudding

I have a data where the key count appears 6 times and it is nested. I'm trying count the number of times it appears with below logic but somewhat I'm close to it not got the exact result.

The problem is child values I'm getting as 7 which I have consoled. but the final count is always 1 seriously I don't know why I'm getting 1. Any help!

let data = [{
  "id": "1",
  "child": [
    {
      "id": "12",
      "child": [
        {
          "id": "123",
          "child": [
           {
            "id": "1234"
           }
          ]
        }
      ]
    },
    {
      "id": "2",
      "child": [
        {
          "id": "22"
        }
      ]
    },
    {
      "id": "3"
    },
    {
      "id": "4",
      "child": [
        {

          "id": "42",
          "child": [
            {

              "id": "43"
            }
          ]
        }
      ]
    }
  ]
}]

const countChild = (arr,cnt = 0) => {
  for (const {child} of arr) {
    cnt = cnt   1
    console.log("child",cnt)
    if(child) countChild(child, cnt)
  }
  return cnt;
};
console.log("Final count",countChild(data))

CodePudding user response：

I would recommend a reduce function for that:

const countData = (arr: any) => {
    return arr.reduce((results: number, elm: any) => {
        if (!!elm.child) {
            results  = (1   countData(elm.child));
        }

        return results;
    }, 0);
};

But if you still want to use your function, it needs to be adapted as below:

const countChild = (arr,cnt = 0) => {
  for (const {child} of arr) {
    if (child)
        cnt = 1   countChild(child, cnt);
    console.log("child",cnt)
  }
  return cnt;
};

CodePudding user response：

you can do something like this

let data = [{
  "id": "1",
  "child": [
    {
      "id": "12",
      "child": [
        {
          "id": "123",
          "child": [
           {
            "id": "1234"
           }
          ]
        }
      ]
    },
    {
      "id": "2",
      "child": [
        {
          "id": "22"
        }
      ]
    },
    {
      "id": "3"
    },
    {
      "id": "4",
      "child": [
        {

          "id": "42",
          "child": [
            {

              "id": "43"
            }
          ]
        }
      ]
    }
  ]
}]

const flatChild = (arr) => 
  arr.flatMap(({id, child}) => [id, ...flatChild(child || [])] ) 

const countChild = arr => flatChild(arr).length



console.log("Final count", countChild(data))

CodePudding user response：

let data = [{
  "id": "1",
  "child": [
    {
      "id": "12",
      "child": [
        {
          "id": "123",
          "child": [
           {
            "id": "1234"
           }
          ]
        }
      ]
    },
    {
      "id": "2",
      "child": [
        {
          "id": "22"
        }
      ]
    },
    {
      "id": "3"
    },
    {
      "id": "4",
      "child": [
        {

          "id": "42",
          "child": [
            {

              "id": "43"
            }
          ]
        }
      ]
    }
  ]
}];

let cnt = 0;

const countChild = (arr) => {
  for (const {child} of arr) {
    cnt = cnt   1;
    console.log("child",cnt);
    if(child) countChild(child);
  }
  return cnt;
};
console.log("Final count",countChild(data));

here simply putting the cnt in global scope so the JS will not make local copies for each recursive function