My array is like so:

 let dup=  [
      {
        "category": "snacks",
        "id": 1,
        "data": [
          {
            "id": 11,
            "title": "choclate",
            "subItem": [],
            "count": 0
          },
          {
            "id": 1,
            "title": "Protein Bar",
            "subItem": [],
            "count": 0
          }
        ]
      },
      {
        "category": "beverages",
        "id": 2,
        "data": [
          {
            "id": 2,
            "title": "Tea",
            "subItem": [
              {
                "id": 1,
                "title": "sugar",
                "status": 1,
                "createdAt": "2021-11-10T03:35:02.500Z",
                "updatedAt": "2021-11-10T03:35:02.500Z"
              }
            ],
            "count": 0
          },
          {
            "id": 3,
            "title": "Coffee",
            "subItem": [
              {
                "id": 1,
                "title": "sugar",
                "status": 1,
                "createdAt": "2021-11-10T03:35:02.500Z",
                "updatedAt": "2021-11-10T03:35:02.500Z"
              }
            ],
            "count": 0
          }
        ]
      }
    ]

I was trying to change the count (just like a shopping cart)

I tried to solve the problem by the function above, but i am not getting the required result. The array is not getting changed.

 function getNewCartItems() {
    let newvar= dup.map(element => (element = element.data.map(item => (item.id === action.item.id ? {...item, count: item.count 1} : item))));
    return newvar;
    }

CodePudding user response：

map will return a new array with the changes made by the callback. You want to return that array. Easiest thing to do would be declare it as a variable and return it:

const newCart = dup.map(...)
return newCart

CodePudding user response：

Solved by the following:

function getNewCartItems() {
      const newArr = state.data?.map(element => {
        return {
          ...element,
          data: element?.data?.map(item => (item.id === action.item.id ? {...item, count: item.count   1} : item)),
        };
      });
      return newArr;
    }