Optimizing Data Fetching with Selective Prefetching

Demonstrate an advanced technique of selective data prefetching with React Query, optimizing the data loading process based on user behavior or certain conditions.
import { useQuery, useQueryClient } from 'react-query';

// Function to prefetch data for a specific item
function usePrefetchItem(itemId) {
  const queryClient = useQueryClient();
  return () => {
    queryClient.prefetchQuery(['item', itemId], fetchItemDetails);
This code snippet demonstrates the use of React Query's useQueryClient hook to prefetch data for a specific item. The usePrefetchItem function takes an itemId as an argument and uses queryClient.prefetchQuery to prefetch the data for that item using the fetchItemDetails function. This technique optimizes data loading by prefetching data based on expected user behavior.
import { useEffect } from 'react';

// Component that prefetches item details on mouse over
function Item({ itemId, onMouseOver }) {
  const prefetchItem = usePrefetchItem(itemId);

  useEffect(() => {
    const prefetchOnHover = () => prefetchItem();
    document.getElementById(`item-${itemId}`).addEventListener('mouseover', prefetchOnHover);

    return () => document.getElementById(`item-${itemId}`).removeEventListener('mouseover', prefetchOnHover);
  }, [itemId, prefetchItem]);

  return <div id={`item-${itemId}`} onMouseOver={onMouseOver}>Hover over me to prefetch item details</div>;
Here, we have a React component that uses the custom usePrefetchItem hook to prefetch data when the mouse is hovered over it. By attaching a mouseover event listener to the component, we call the prefetchItem function, which was previously set up to prefetch the data for the given itemId. This technique demonstrates how to use selective prefetching to optimize the user experience by prefetching data based on user interaction.