In-memory caching with node-cache in Express - Mini Project: Build & Apply

In-memory caching with node-cache in Express

📖 Scenario: You are building a simple Express server that fetches user data. To make it faster, you want to store some data temporarily in memory so the server does not fetch it again and again.

🎯 Goal: Create an Express server that uses node-cache to store user data in memory. The server should return cached data if available, or fetch and cache it if not.

📋 What You'll Learn

Create an Express app with a GET route at /user/:id

Use node-cache to store user data in memory

Set a cache time-to-live (TTL) of 10 seconds

Return cached data if it exists, otherwise simulate fetching data and cache it

💡 Why This Matters

🌍 Real World

In-memory caching helps speed up web servers by storing frequently requested data temporarily, reducing database or API calls.

💼 Career

Understanding caching is important for backend developers to improve app performance and scalability.

1

Setup Express app and import node-cache

Write code to import express and NodeCache from node-cache. Then create an Express app by calling express() and assign it to a variable called app.

Express

// Your code here

Need a hint?

Use import statements to bring in the modules. Then call express() to create the app.

2

Create a cache instance with 10 seconds TTL

Create a new NodeCache instance called cache with a time-to-live (TTL) option set to 10 seconds.

Express

import express from 'express';
import NodeCache from 'node-cache';

const app = express();

// Create cache instance with 10 seconds TTL
// Your code here

Need a hint?

Use new NodeCache({ stdTTL: 10 }) to create the cache with 10 seconds TTL.

3

Add GET route to use cache for user data

Add a GET route handler on /user/:id using app.get. Inside the handler, get the id from req.params. Check if the user data exists in cache using cache.get(id). If it exists, return it as JSON. If not, simulate fetching user data by creating an object { id, name: `User ${id}` }, store it in cache with cache.set(id, userData), and return it as JSON.

Express

import express from 'express';
import NodeCache from 'node-cache';

const app = express();

const cache = new NodeCache({ stdTTL: 10 });

// Add GET /user/:id route with caching
// Your code here

Need a hint?

Use app.get with /user/:id. Use req.params.id to get the id. Use cache.get(id) to check cache. If no cache, create user data and store with cache.set(id, userData).

4

Start the Express server on port 3000

Add code to start the Express server by calling app.listen on port 3000. Provide a callback function that logs the message 'Server running on port 3000'.

Express

import express from 'express';
import NodeCache from 'node-cache';

const app = express();

const cache = new NodeCache({ stdTTL: 10 });

app.get('/user/:id', (req, res) => {
  const id = req.params.id;
  const cachedUser = cache.get(id);
  if (cachedUser) {
    return res.json(cachedUser);
  }
  const userData = { id, name: `User ${id}` };
  cache.set(id, userData);
  res.json(userData);
});

// Start server on port 3000
// Your code here

Need a hint?

Use app.listen(3000, () => { console.log('Server running on port 3000') }) to start the server.