Welcome to the first lesson of our Redis course! In this unit, we'll start with the very basics — connecting to a Redis server. Understanding how to establish this connection is essential since it forms the backbone of all the operations you'll perform with Redis. By the end of this lesson, you’ll be confident in setting up a connection to a Redis server and verifying that connection through simple operations.

In this lesson, you will learn how to:

1. Connect to a Redis server using JavaScript.
2. Verify your connection by storing and retrieving a value.

Here’s the simple code you’ll be working with:

JavaScript
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1import { createClient } from 'redis';
2
3const client = createClient({
4  url: 'redis://localhost:6379'
5});
6
7client.on('error', err => console.log('Redis Client Error', err));
8
9await client.connect();
10
11// Verify the connection by setting and getting a value
12await client.set('name', 'Redis Learner');
13let value = await client.get('name');
14console.log(`Stored string in Redis: ${value}`);
15
16await client.del('name');
17value = await client.get('name');
18console.log(`Stored string in Redis: ${value}`);
19
20await client.disconnect();

Let's break down the code:

• We import the createClient function from the redis package, which provides the JavaScript interface to Redis.
• We use the createClient method to create a client and connect to the Redis server running on localhost at port 6379. Note, that if you do not provide the url option, the client will default to connecting to localhost:6379.
• We listen for any errors that may occur during the connection using the client.on('error') event listener. If an error occurs, we log it to the console with the message 'Redis Client Error' followed by the error message.
• We connect to the Redis server by calling await client.connect().
• We use the set method to store a key-value pair in Redis, where the key is 'name' and the value is 'Redis Learner'.
• We retrieve the value stored in Redis using the get method, store it in the value variable, and print it. Notice that we use the await keyword to wait for the asynchronous operation to complete.
• Next, we use del to delete the key 'name' from Redis. After deleting the key, we attempt to retrieve the value again using the get method. Since the key has been deleted, the value will be null.
• Finally, we disconnect from the Redis server using the disconnect method to ensure cleanup.

Establishing a connection to a Redis server is the first step in using the various features Redis has to offer, from fast data access to caching and message brokering. Without this fundamental step, you wouldn't be able to use Redis effectively. Knowing how to connect to a Redis server will enable you to start experimenting with Redis's powerful features, such as data structures and atomic operations.