Caching, Background Updates, and Retries

🔁 Caching, Background Updates, and Retries in React

When dealing with asynchronous data in React, optimizing for performance and user experience is key. Instead of constantly re-fetching data, we can cache it, update it in the background, and retry failed requests — all without burdening the UI. In this guide, we’ll explore how tools like TanStack Query and React 19 features help you achieve just that. 🚀⚡

🧠 What Is Data Caching?

Caching is the practice of storing previously fetched data so it can be reused without making another API call. This drastically improves perceived performance and reduces unnecessary network requests.

const { data } = useQuery({
  queryKey: ['users'],
  queryFn: fetchUsers
});

✨ Once this data is fetched, TanStack Query stores it in memory — available instantly on future renders.

📦 Default Cache Behavior

• ⏱️ Cached data stays "fresh" for 5 minutes by default
• 📦 It’s keyed by queryKey, allowing fine-grained control
• ♻️ On re-renders, React skips the network request if cached data exists

🎯 Customizing Cache Time

You can control how long data stays in the cache:

useQuery({
  queryKey: ['products'],
  queryFn: fetchProducts,
  cacheTime: 1000 * 60 * 10 // 10 minutes
});

⏳ After this period, the data will be garbage collected unless still being used.

🔄 Background Refetching

TanStack Query doesn’t just cache — it also updates stale data in the background without blocking the UI.

useQuery({
  queryKey: ['posts'],
  queryFn: fetchPosts,
  staleTime: 1000 * 60 // consider fresh for 1 min
});

• ⏱️ During the staleTime, no background updates occur
• 🔄 After staleTime, refetching occurs silently in the background
• 🔁 Updates the UI automatically when fresh data arrives

⚠️ Retrying Failed Requests

Failed API calls don’t have to ruin the user experience. With built-in retry logic, you can automatically re-attempt failed queries:

useQuery({
  queryKey: ['comments'],
  queryFn: fetchComments,
  retry: 3, // Retry up to 3 times
  retryDelay: attemptIndex => Math.min(1000 * 2 ** attemptIndex, 30000) // exponential backoff
});

• 🔄 Retries are automatic — no need to write retry logic manually
• 🧠 Customizable per query

📱 Real-World Scenario: Chat Messages

Imagine you're building a chat app where messages are fetched frequently. Here's how to optimize using caching, background refresh, and retry:

useQuery({
  queryKey: ['chat', chatId],
  queryFn: () => fetch(`/api/chat/${chatId}`),
  refetchInterval: 5000,       // Poll every 5 seconds
  staleTime: 1000 * 10,        // Consider data fresh for 10 sec
  retry: 2,
  cacheTime: 1000 * 60 * 5     // Cache for 5 minutes
});

• 📡 Keeps messages fresh
• ✅ Avoids UI blocking when data is stale
• 🛡️ Auto-recovers from temporary failures

🔌 Additional Features

• 🔍 onSuccess / onError: Callbacks after query success or failure
• 📉 refetchOnWindowFocus: True by default — refreshes when user switches back to the tab
• 📲 pagination & infinite queries: Easily handled with helpers

useQuery({
  queryKey: ['users'],
  queryFn: fetchUsers,
  onSuccess: (data) => console.log('Fetched!', data),
  onError: (error) => alert('Try again later!')
});

📋 Summary

• 🧠 Caching saves previously fetched data to prevent re-fetching
• 🔁 Background updates silently refresh data after it becomes stale
• ⚠️ Retries recover from temporary network failures automatically
• ⚙️ TanStack Query gives you full control over all of it

🚀 Final Thoughts

When building real-world apps, user experience matters more than raw functionality. With caching, background refetching, and retry logic, you can build fast, resilient apps that feel buttery-smooth. Combine these with Server Components or SSR for even better results. Optimize once — and scale with confidence. ⚛️🔥