Convert flat array of array into nested objects

Question

I have an array of values and I want to convert them into nested objects if the category i.e 1st element exists then the next subcategories are pushed in this. Can we achieve this, I am beginner please help

for example:

    const newCat = [
                     [
                        "Grocery", // category
                        "Food & Drink", // sub-category
                        "Snacks, Crisps and Sweets", // sub-sub-category
                    ],
                    [
                        "Grocery",
                        "Canned, Dry & Packaged Food",
                        "Pickled Foods",
                    ],
                    [
                        "Grocery",
                        "Food & Drink",
                    ],
                    [
                        "Grocery",
                        "Food & Drink",
                        "Nuts, Dates & Dried Fruits",
                    ],
                    [
                        "Grocery",
                        "World Specialities",
                        "India",
                    ],

                  ]

OUTPUT -
[
    {
    CategoryName: "Grocery",
    SubCategories: [
      {
        CategoryName: "Food & Drink",
        SubCategories: [
          {
            CategoryName: "Snacks, Crisps, and Sweets",
          },
        ],
      },
      {
        CategoryName: "Canned, Dry & Packaged Food",
        SubCategories: [
          {
            CategoryName: "Pickled Foods",
          },

        ],

      },
    ],
  }
]

Answer 1

function flatArray(arr) {
  const result = [];
  for (let item of arr) {
    const [c1, c2, c3] = item;
    const findC1 = result.find(c => c.categoryName === c1);
    if (findC1) {
      if (!c2) {
        continue;
      }
      const findC2 = findC1.subCategorys.find(c => c.categoryName === c2);
      if (findC2) {
        if (!c3) {
          continue;
        }
        findC2.subCategorys.push(c3);
      } else {
        findC1.subCategorys.push({
          categoryName: c2,
          subCategorys: [c3]
        });
      }
    } else {
      result.push({
        categoryName: c1,
        subCategorys: [
          {
            categoryName: c2,
            subCategorys: [c3]
          }
        ]
      })
    }
  }  
  
  return result;
}


// Test case
const newCat = [
   [
      "Grocery", // category
      "Food & Drink", // sub-category
      "Snacks, Crisps and Sweets", // sub-sub-category
  ],
  [
      "Grocery",
      "Canned, Dry & Packaged Food",
      "Pickled Foods",
  ],
  [
      "Grocery",
      "Food & Drink",
  ],
  [
      "Grocery",
      "Food & Drink",
      "Nuts, Dates & Dried Fruits",
  ],
  [
      "Grocery",
      "World Specialities",
      "India",
  ],

];

console.log(flatArray(newCat));