---
title: "Client.decrBy(key, decrement) | Grafana k6 documentation"
description: "Decrements the number stored at `key` by `decrement`."
---

# Client.decrBy(key, decrement)

Decrements the number stored at `key` by `decrement`. If the key does not exist, it is set to zero before performing the operation.

### Parameters

Expand table

| Parameter   | Type   | Description                |
|-------------|--------|----------------------------|
| `key`       | string | the key to decrement.      |
| `decrement` | number | the amount to decrement by |

### Returns

Expand table

| Type              | Resolves with                                                                 | Rejected when                                                                                                                                        |
|-------------------|-------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------|
| `Promise<number>` | On success, the promise resolves with the value of `key` after the decrement. | If the key contains a value of the wrong type, or contains a string that cannot be represented as an integer, the promise is rejected with an error. |

### Example

JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```javascript
import redis from 'k6/x/redis';

// Instantiate a new redis client
const redisClient = new redis.Client('redis://localhost:6379');

export default async function () {
  await redisClient.set('mykey', 10, 0);

  const value = await redisClient.decrBy('mykey', 2);
  if (value !== 8) {
    throw new Error('mykey should have been 8');
  }
}
```