How to cache requests on the frontend and how to manage caching?

Caching requests on the frontend helps reduce server load and speed up data loading. Main methods:

• HTTP Caching: using Cache-Control, ETag, Last-Modified headers to manage caching at the browser and proxy level.
• In-memory caching: storing request results in variables or state (e.g., in React) for reuse without new requests.
• IndexedDB or localStorage: for long-term data storage between sessions.

Cache management includes:

• Setting cache lifetime (TTL).
• Invalidating cache when data changes (e.g., on event or version).
• Using libraries (e.g., React Query, SWR) that automate caching and data updating.

Example using fetch and simple in-memory cache:

const cache = new Map();

async function fetchWithCache(url) {
  if (cache.has(url)) {
    return cache.get(url);
  }
  const response = await fetch(url);
  const data = await response.json();
  cache.set(url, data);
  return data;
}

This approach is simple but requires manual cache invalidation management.