@suman-malik-repo/snapcache

Express middleware for SHA256 ETag hashing and cache acceleration. Pairs with the SnapCache CDN script for instant client-side caching.

Install

npm install @suman-malik-repo/snapcache

Usage

Global Middleware

const express = require('express');
const snapCache = require('@suman-malik-repo/snapcache');

const app = express();

// Auto ETag for all GET responses
app.use(snapCache({
  exclude: ['/auth', '/admin'],
  cacheControl: 'private, no-cache'
}));

app.get('/api/users', (req, res) => {
  res.json({ users: [...] }); // ETag auto-added
});

Per-Route Helpers

app.get('/api/user/:id', async (req, res) => {
  const user = await db.getUser(req.params.id);
  res.snapCache(user);     // or res.sendWithETag(user)
});

Options

| Option | Type | Default | Description | |--------|------|---------|-------------| | exclude | string[] | [] | Routes to skip | | cacheControl | string | 'private, no-cache' | Cache-Control header | | weak | boolean | false | Use weak ETags |

How It Works

1. Server computes SHA256(JSON.stringify(data)) → ETag
2. Client sends If-None-Match: "etag" on repeat requests
3. If match → 304 Not Modified (no body sent)
4. If different → 200 with new data + new ETag

Client SDK

Add the CDN script to your frontend for IndexedDB caching + SWR:

<script src="https://snapcache.ogensync.com/sdk.js"></script>

License

MIT