---
title: "Client.getSet(key, value) | Grafana k6 documentation"
description: "Atomically sets `key` to `value` and returns the old value stored at `key`."
---

# Client.getSet(key, value)

Atomically sets `key` to `value` and returns the value previously stored at `key`.

### Parameters

Expand table

| Parameter | Type                       | Description            |
|-----------|----------------------------|------------------------|
| `key`     | string                     | the key to get and set |
| `value`   | string, number, or boolean | the value to set       |

### Returns

Expand table

| Type              | Resolves with                                                        | Rejected when                                                                                    |
|-------------------|----------------------------------------------------------------------|--------------------------------------------------------------------------------------------------|
| `Promise<string>` | On success, the promise resolves with the old value stored at `key`. | If `key` does not exist, or does not hold a string value, 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', 'oldvalue', 0);
  await redisClient.getSet('mykey', 'newvalue');
  await redisClient.getDel('mykey');
}
```