Using Query Prefetching

Example on how to prefetch data with React Query's `useQuery` and `prefetchQuery` methods, improving user experience by loading data before it's requested.

import { useQuery, useQueryClient } from 'react-query';

function Todos() {
  const queryClient = useQueryClient();

  // Prefetch the Todos whenever the mouse is over the Todos link
  const prefetchTodos = () => {
    queryClient.prefetchQuery('todos', fetchTodos)
  };

  return (
    <div onMouseEnter={prefetchTodos}>
      Show Todos
    </div>
  );
}

async function fetchTodos() {
  // Fetch Todos from an API
  const response = await fetch('/api/todos');
  return response.json();
}

This code demonstrates how to prefetch data for a Todos component using React Query's `useQueryClient` and `prefetchQuery` methods. It preloads the data when the mouse enters the component area, reducing load time when the data is actually requested.

import { useQuery } from 'react-query';

function TodosList() {
  const { data, status } = useQuery('todos', fetchTodos);

  if (status === 'loading') return <div>Loading...</div>;
  if (status === 'error') return <div>Error fetching data</div>;

  return (
    <ul>
      {data.map(todo => (
        <li key={todo.id}>{todo.title}</li>
      ))}
    </ul>
  );
}

This segment of the code demonstrates how to request and display the Todos using React Query's `useQuery` hook. If the Todos have been prefetched, React Query will use the cached data instead of refetching it, hence making the data load instantly.