How to parse json one structure to another structure in optimize way using javascript?

Question

I have below json

let result = [
    {
        "category": "Social Media",
        "category_id": 6,
        "sub_category": "Facebook",
        "sub_category_id": 5
    },
    {
        "category": "Social Media",
        "category_id": 6,
        "sub_category": "Instagram",
        "sub_category_id": 7
    },
    {
        "category": "Tech",
        "category_id": 3,
        "sub_category": "Angular",
        "sub_category_id": 1
    },
    {
        "category": "Tech",
        "category_id": 3,
        "sub_category": "Javascript",
        "sub_category_id": 6
    }
]

I am trying to active below

[
  {
    "category": "Social Media",
    "category_id": 6,
    "sub_category": [
      {
        "sub_category": "Instagram",
        "sub_catgory_id": 7
      },
      {
        "sub_category": "Facebook",
        "sub_catgory_id": 5
      }
    ]
  },
  {
    "category": "Tech",
    "category_id": 3,
    "sub_category": [
      {
        "sub_category": "Angular",
        "sub_catgory_id": 1
      },
      {
        "sub_category": "Javascript",
        "sub_catgory_id": 6
      }
    ]
  }
]

Below code i have tried. Can anyone help me to identify where i am doing wrong?

let result = [{
    "category": "Social Media",
    "category_id": 6,
    "sub_category": "Facebook",
    "sub_category_id": 5
  },
  {
    "category": "Social Media",
    "category_id": 6,
    "sub_category": "Instagram",
    "sub_category_id": 7
  },
  {
    "category": "Tech",
    "category_id": 3,
    "sub_category": "Angular",
    "sub_category_id": 1
  },
  {
    "category": "Tech",
    "category_id": 3,
    "sub_category": "Javascript",
    "sub_category_id": 6
  }
];

const dataArr = [];
result.forEach((value, key) => {
  let catgeory = {
    category: value.category,
    category_id: value.category_id,
    sub_category: []
  };

  catgeory.sub_category.push({
    sub_category: value.sub_category,
    sub_category_id: value.sub_category_id
  })

  dataArr.push(catgeory);
});

console.log(dataArr);

Answer 1

Explanation is in comments.

const data = {}

let result = [{"category":"Social Media","category_id":6,"sub_category":"Facebook","sub_category_id":5},{"category":"Social Media","category_id":6,"sub_category":"Instagram","sub_category_id":7},{"category":"Tech","category_id":3,"sub_category":"Angular","sub_category_id":1},{"category":"Tech","category_id":3,"sub_category":"Javascript","sub_category_id":6}];

// loop over each records
result.forEach((value) => {
  // data will be object with key as category and value as category, category_id & sub_category array.
  // get data[value.category], if not exist then create new object and assign.
  data[value.category] = data[value.category] || {
    category: value.category,
    category_id: value.category_id,
    sub_category: []
  };
  // push sub_category values.
  data[value.category].sub_category.push({
    sub_category: value.sub_category,
    sub_category_id: value.sub_category_id
  });
});

// we need array of values only so use Object.values(data)
let dataArr = Object.values(data);
console.log(dataArr);