Redis with Node.js (ioredis) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is ioredis in the context of Node.js?

ioredis is a popular Node.js library that helps you connect and work with Redis easily. It provides simple commands to store, retrieve, and manage data in Redis from your Node.js app.

beginner

How do you create a new Redis client using ioredis in Node.js?

<pre>const Redis = require('ioredis');
const redis = new Redis();</pre><p>This code connects your Node.js app to Redis using default settings (localhost, port 6379).</p>

beginner

How do you set and get a value in Redis using ioredis?

<pre>await redis.set('key', 'value');
const value = await redis.get('key');</pre><p>This stores 'value' under 'key' and then retrieves it.</p>

intermediate

What is the benefit of using async/await with ioredis commands?

Using async/await makes your code easier to read and write by handling asynchronous Redis commands in a clear, step-by-step way without nested callbacks.

intermediate

How can you handle Redis connection errors with ioredis?

redis.on('error', (err) => {
  console.error('Redis error:', err);
});

This listens for errors and logs them, helping you catch connection problems.

Which command creates a new Redis client using ioredis with default settings?

A const redis = new Client();

B const redis = Redis.connect();

C const redis = new Redis();

D const redis = Redis.createClient();

The correct way is const redis = new Redis(); which creates a new client with default localhost and port.

How do you store a value 'hello' under the key 'greet' in Redis using ioredis?

A redis.set('hello', 'greet');

B redis.set('greet', 'hello');

C redis.put('greet', 'hello');

D redis.save('greet', 'hello');

The syntax is redis.set('key', 'value');, so redis.set('greet', 'hello'); stores 'hello' under 'greet'.

What does the await keyword do when used with ioredis commands?

A It pauses code until the Redis command finishes.

B It runs the command in the background.

C It cancels the Redis command.

D It converts the command to a string.

await waits for the Redis command to complete before moving on, making asynchronous code easier to read.

How can you listen for Redis connection errors in ioredis?

A redis.error(callback);

B redis.catchError(callback);

C redis.listen('error', callback);

D redis.on('error', callback);

You use redis.on('error', callback); to handle errors emitted by the Redis client.

Which of these is NOT a feature of ioredis?

A Automatically creates SQL tables

B Provides promise-based commands

C Supports Redis clusters

D Handles reconnection automatically

ioredis works with Redis, which is a key-value store, not SQL databases, so it does not create SQL tables.

Explain how to connect to Redis and set a key-value pair using ioredis in Node.js.

Think about the steps from importing the library to storing data.

Describe how to handle errors when working with Redis using ioredis.

Consider how Node.js event listeners work for error events.