Creating a Reducer for Analytics Data

Provide a code example of a reducer function that handles updating parts of the state related to analytics data when relevant actions are dispatched.

const analyticsReducer = (state = { viewCounts: {}, salesData: [] }, action) => {
  switch (action.type) {
    case 'INCREMENT_VIEW_COUNT':
      const { page } = action.payload;
      return {
        ...state,
        viewCounts: {
          ...state.viewCounts,
          [page]: (state.viewCounts[page] || 0) + 1
        }
      };
    case 'SET_SALES_DATA':
      const { salesData } = action.payload;
      return {
        ...state,
        salesData
      };
    // handle other actions
    default:
      return state;
  }
};

Reducer for handling analytics data. It responds to two action types: 'INCREMENT_VIEW_COUNT' which increments a view count for a specific page and 'SET_SALES_DATA' which sets the sales data. The state shape consists of 'viewCounts', an object keyed by page names with values being the count, and 'salesData', an array of sales records.