grouping by column

groupBy.js

const data = [
  {
    product_id: '2',
    category_id: '13',
    description: 'Anxious Armadillo',
    price: '133',
    quantity: '339',
  },
  {
    product_id: '20',
    category_id: '13',
    description: 'Tender Tapir',
    price: '22',
    quantity: '490',
  },
  {
    product_id: '25',
    category_id: '20',
    description: 'Uptight Unicorn',
    price: '87',
    quantity: '376',
  },
  {
    product_id: '25',
    category_id: '20',
    description: 'Product 2',
    price: '87',
    quantity: '376',
  },
  {
    product_id: '25',
    category_id: '10',
    description: 'Product 2',
    price: '87',
    quantity: '376',
  },
  {
    product_id: '25',
    category_id: '15',
    description: 'Product 2',
    price: '87',
    quantity: '376',
  },
];

const find = (acc, cur, el) => acc.find(obj => obj[el] == cur[el]);

const flatten = groupBy => (acc, cur) => {
  const getNode = find(acc, cur, groupBy);

  getNode
    ? getNode.products.push({
        product_id: cur.product_id,
        description: cur.description,
        price: cur.price,
        quantity: cur.quantity,
      })
    : acc.push({
        [groupBy]: cur[groupBy],
        products: [
          {
            product_id: cur.product_id,
            description: cur.description,
            price: cur.price,
            quantity: cur.quantity,
          },
        ],
      });
  return acc;
};

const group = (obj, groupBy = 'category_id') =>
  obj.reduce(flatten(groupBy), []);

console.log(group(data, 'category_id'));