Operations with Numbers

Welcome back! Now that you've learned how to work with numbers in Redis, it's time to build on that knowledge and explore some basic operations with these numbers. This lesson will show you how to perform operations like incrementing, decrementing, and modifying numeric values directly in Redis.

In this lesson, you will learn how to:

1. Increment and decrement numeric values.
2. Modify numeric values using operations such as increments by a floating point.

Here's the code snippet that we'll be working with:

import { createClient } from 'redis';

const client = createClient();
client.on('error', (err) => console.log('Redis Client Error', err));
await client.connect();

// Setting and getting string values
await client.set('count', 5);
await client.set('completion_rate', 95.5);
await client.set('duration', 0);

await client.decr('count'); // 4
await client.decrBy('count', 2); // 2
await client.incr('duration'); // 1
await client.incrBy('duration', 2); // 3
await client.incrByFloat('completion_rate', 1.5); // 97

// Fetch the values and log them
const count = await client.get('count');
const duration = await client.get('duration');
const completion_rate = await client.get('completion_rate');

console.log(`Course count: ${count}`); // 2
console.log(`Duration: ${duration}`); // 3
console.log(`Completion rate: ${completion_rate}`); // 97

await client.disconnect();

• After setting initial values for count, completion_rate, and duration, we perform various operations:
  • decr operation decrements the value of count by 1, and decrBy decrements it by the specified value, in this case, 2. So, the final value of count is 2.
  • incr operation increments the value of duration by 1, and incrBy increments it by the specified value, in this case, 2. So, the final value of duration is 3.
  • incrByFloat increments the value of completion_rate by the specified floating-point value, in this case, 1.5. So, the final value of completion_rate is 97.
• At the end, we fetch the updated values of count, duration, and completion_rate and log them to the console.

Note, that the incr, decr, incrBy, and decrBy operations cannot be applied to keys that contain floating-point values, that's why we use incrByFloat to increment floating-point values. Note, that in order to decrement floating-point values, you can use incrByFloat with a negative value.