Recursively manipulate mock json server

inputdata.json

[
    {
      "id": 0,
      "title": "1",
      "sublist": [
        {
          "id": 1,
          "title": "1.1",
          "sublist": [
            {
              "id": 2,
              "title": "1.1.1",
              "sublist": []
            },
            {
              "id": 3,
              "title": "1.1.2",
              "sublist": []
            }
          ]
        },
        {
          "id": 4,
          "title": "1.2",
          "sublist": []
        },
        {
          "id": 5,
          "title": "1.3",
          "sublist": [
            {
              "id": 6,
              "title": "1.3.1",
              "sublist": [
                {
                  "id": 7,
                  "title": "1.3.1.1",
                  "sublist": []
                },
                {
                  "id": 8,
                  "title": "1.3.1.2",
                  "sublist": []
                }
              ]
            },
            {
              "id": 9,
              "title": "1.3.2",
              "sublist": []
            },
            {
              "id": 10,
              "title": "1.3.3",
              "sublist": []
            }
          ]
        },
        {
          "id": 11,
          "title": "1.4",
          "sublist": []
        }
      ]
    },
    {
      "id": 12,
      "title": "2",
      "sublist": [
        {
          "id": 13,
          "title": "2.1",
          "sublist": []
        },
        {
          "id": 14,
          "title": "2.2",
          "sublist": []
        },
        {
          "id": 15,
          "title": "2.3",
          "sublist": []
        },
        {
          "id": 16,
          "title": "2.4",
          "sublist": []
        },
        {
          "id": 17,
          "title": "2.5",
          "sublist": [
            {
              "id": 18,
              "title": "2.6",
              "sublist": [
                {
                  "id": 19,
                  "title": "2.6.1",
                  "sublist": []
                },
                {
                  "id": 20,
                  "title": "2.6.2",
                  "sublist": []
                },
                {
                  "id": 21,
                  "title": "2.6.3",
                  "sublist": [
                    {
                      "id": 22,
                      "title": "2.6.3.1",
                      "sublist": [
                        {
                          "id": 23,
                          "title": "2.6.3.1.1",
                          "sublist": []
                        },
                        {
                          "id": 24,
                          "title": "2.6.3.1.2",
                          "sublist": []
                        }
                      ]
                    },
                    {
                      "id": 25,
                      "title": "2.6.4",
                      "sublist": []
                    }
                  ]
                }
              ]
            }
          ]
        }
      ]
    },
    {
      "id": 26,
      "title": "3",
      "sublist":[]
    },
    {
      "id":27,
      "title": "4",
      "sublist":[]
    }
  ]
  

main.ts

const content = require(`./inputdata.json`);
const fs = require('fs')
let outputdata = content

let i = 0;

function NestedChaps(chapter) {

    chapter.id = i; // adding "id" attribute to all of the objects   
    i = i + 1;
    console.log("id:" + chapter.id + "," + "title:" + chapter.title)
    const nestedChaps = (chapter.sublist || []).map((subchapter, k) => {

        return (
            NestedChaps(subchapter)
        )
    }
    )

    nestedChaps;
}

outputdata.map((chapter, i) => {

    return (

        NestedChaps(chapter)
    )


}
)

fs.writeFileSync('outputdata.json', JSON.stringify(outputdata)); // writing the result to new file