Caching Basics

8 examples to get you started with caching for Node.js APIs - 6 basic and 2 intermediate.

Prerequisites

npm install ioredis
npm install -D typescript@5.6 tsx @types/node

Run Redis locally: docker run -d -p 6379:6379 redis:7. See ioredis for connection details.

Basic Examples

1. Cache-Aside Read

import Redis from "ioredis";
 
const redis = new Redis(process.env.REDIS_URL!);
 
export async function getProduct(sku: string, loadFromDb: (sku: string) => Promise<Product | null>) {
  const key = `product:${sku

• App owns consistency - DB is source of truth
• TTL (EX 300) bounds staleness
• On cache miss, only one code path loads DB

Related: ioredis - client setup

2. TTL Strategy

• Shorter TTL is simpler than perfect invalidation for low-risk reads
• Document max staleness per endpoint in API docs

3. Cache Delete on Write

export async function updateProduct(sku: string, data: Partial<Product>, save: () => Promise<Product>) {
  const updated = await save();
  await redis.del

• Write-through DB first, then invalidate cache
• For related keys, delete pattern or maintain reverse index set
• Missing invalidation causes stale reads until TTL expires

4. Namespaced Keys

const NS = `api:${process.env.APP_ENV}:v1`;
 
function productKey(sku: string) {
  return `${NS}:product:${sku}`;
}

• Prefix by environment so staging never hits prod keys
• Bump v1 to v2 on breaking cache shape changes
• Avoid unbounded key cardinality (no raw user search strings)

5. Graceful Degradation on Redis Down

export async function getWithFallback<T>(
  fetchCache: () => Promise<T | null>,
  fetchOrigin: () => Promise<T>
): Promise<T> {

• Redis outage should not take down read endpoints
• Log cache errors; alert on sustained failure
• Writes that depend on Redis (locks, rate limits) may still fail closed

6. JSON Serialization Cost

await redis.set(key, JSON.stringify(value), "EX", ttl);
const raw = await redis.get(key);
const value = raw ? (JSON.parse(raw) as T) : null

• Large objects hurt CPU and bandwidth - cache DTOs not full ORM graphs
• Consider MessagePack only when profiling proves JSON is hot
• See JSON Serialization Cost

Intermediate Examples

7. Stampede Prevention (Single-Flight Lock)

async function getOrLoad(key: string, ttlSec: number, loader: () => Promise<string>) {
  const hit = await redis.get(key);
  if (hit) return hit;
 

• When hot key expires, one loader repopulates; others wait or retry get
• Lock TTL prevents deadlocks if loader crashes
• Alternative: probabilistic early expiration

Related: Distributed Locks - lock caveats

8. Cache-Aside vs Read-Through

• Node APIs almost always implement cache-aside explicitly
• Queue workers warm caches after bulk DB updates

FAQs

Related

• ioredis - connection and pipelines
• Session Stores - Redis sessions
• Distributed Locks - coordination
• Caching Best Practices - team checklist
• Performance Basics - latency budgets

Stack versions: This page was written for Node.js 24.18.0 (Active LTS), npm 10+, TypeScript 5.6+, Express 5, Fastify 5, and NestJS 11.