Hono Mem Cache

A lightweight, in-memory caching middleware for Hono applications.

Features

• 🚀 Simple LRU-based memory caching
• ⏱️ Configurable time-to-live (TTL) for cached responses
• 🔑 Custom cache key generation
• ✅ Custom response validation for caching
• 🔄 Automatic cache headers

Installation

# npm
npm install hono-mem-cache

# yarn
yarn add hono-mem-cache

# pnpm
pnpm add hono-mem-cache

Usage

Basic Example

import { Hono } from 'hono'
import { memCache } from 'hono-mem-cache'

const app = new Hono()

// Apply the middleware to cache responses
app.use(
  '/api/*',
  memCache({
    max: 100, // Maximum number of items in cache
    ttl: 60000, // TTL of 60 seconds
  })
)

app.get('/api/users', (c) => {
  // This response will be cached
  return c.json({ users: ['user1', 'user2'] })
})

app.post('/api/users', (c) => {
  // POST requests won't be cached by default
  return c.json({ success: true })
})

Custom Cache Key Generator

You can customize how cache keys are generated:

import { Hono } from 'hono'
import { memCache } from 'hono-mem-cache'

const app = new Hono()

app.use(
  '/api/*',
  memCache({
    max: 100,
    ttl: 30000, // 30 seconds
    key: (c) => {
      // Cache based on URL and a custom header
      const authHeader = c.req.header('Authorization')
      if (!authHeader) return null // Don't cache if not authenticated

      return `${c.req.method}:${c.req.url}:${authHeader}`
    }
  })
)

Custom Response Validation

You can control whether a response should be cached by providing a custom validate function. This function receives the response context and should return true to cache the response or false to skip caching.

import { Hono } from 'hono'
import { memCache } from 'hono-mem-cache'

const app = new Hono()

app.use(
  '/api/*',
  memCache({
    max: 100,
    ttl: 30000, // 30 seconds
    validate: (c) => {
      // Only cache responses with a 200 status code and a specific header
      return c.res.status === 200 && c.res.headers.get('Cache-Control') === 'public'
    }
  })
)

API

memCache(options)

Creates a Hono middleware function for caching responses.

Options

| Name | Type | Description | |------|------|-------------| | max | number | Required. The maximum number of items in the cache. | | ttl | number | Optional. Time-to-live in milliseconds. If not set, cache items won't expire. | | key | (c: Context) => string \| null \| Promise<string \| null> | Optional. A function to generate cache keys. Return null to skip caching. | | validate | (c: Context) => boolean \| Promise<boolean> | Optional. A function to determine if a response should be cached. |

Cache Headers

The middleware automatically adds the following response header:

• X-Cache: HIT - When serving a cached response
• X-Cache: MISS - When a response wasn't found in cache

How It Works

1. The middleware generates a cache key based on the request.
2. If a cached response exists, it is served immediately.
3. If no cached response exists:
   1. The request flows through the middleware chain.
   2. Only valid responses are cached for future requests.

By default, only GET requests with successful (2xx) responses are cached.

License

This project is licensed under either:

• MIT License
• Apache License 2.0

You can choose the license that best suits your needs.