I don't know how to really reduce the method, I tried to use this to obtain the next JSON, but it obviously did not work.

    {
        "w_elem": [
            {
                "item": [
                    {"type": "type_a","price": "100","discount": "10"},
                    {"type": "type_b","price": "120","discount": "12"},
                    {"type": "type_a","price": "165","discount": "10"}
                ],
                "user": "1001",
                "userType": "A"
            },
            {
                "item": [
                    {"type": "type_a","price": "85","discount": "5"},
                    {"type": "type_a","price": "15","discount": "0"}
                ],
                "user": "1002",
                "userType": "B"
            }
        ]
    }```

  w_elem.forEach(elem => {
    let user= elem.user;

    let aa = Object.values(elem.item.reduce((acc, {type, price, discount}) => {
      acc[type] = acc[type] || {type, price: 0, discount: 0, Count: 0};
      acc[type].price+= Number(price);
      acc[type].discount+= Number(discount);
      acc[type].Count += 1;
      return acc;
    },{}));
  });```

i tried to do the next

        {
            "user": "1001",
            "item": [
                {"type": "type_a","price": "265","discount": "20"},
                {"type": "type_b","price": "120","discount": "12"},
            ]
        },
        {
            "user": "1002",
            "item": [
                {"type": "type_a","price": "85","discount": "5"},
                {"type": "type_b","price": "15","discount": "0"}
            ]
        }
    ]

i dont understand how mantain the struct and only group items by type using reduce