---
title: "Params | Grafana k6 documentation"
description: "Used for setting various WebSocket request-specific parameters such as headers, tags, etc."
---

> For a curated documentation index, see [llms.txt](/llms.txt). For the complete documentation index, see [llms-full.txt](/llms-full.txt).

# Params

`Params` is an object used by the WebSocket constructor. The `Params` object contains request-specific options, such as headers that should be inserted into the connection initialization request.

Expand table

| Name                 | Type                                                              | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|----------------------|-------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `Params.compression` | string                                                            | Compression algorithm to be used by the WebSocket connection. The only supported algorithm currently is `deflate`.                                                                                                                                                                                                                                                                                                                                                |
| `Params.jar`         | [http.CookieJar](/docs/k6/next/javascript-api/k6-http/cookiejar/) | The cookie jar that will be used when making the initial HTTP request to establish the WebSocket connection. If empty, the [default VU cookie jar](/docs/k6/next/javascript-api/k6-http/cookiejar/) will be used.                                                                                                                                                                                                                                                 |
| `Params.headers`     | object                                                            | Custom HTTP headers in key-value pairs that will be added to the initial HTTP request to establish the WebSocket connection. Keys are header names and values are header values.                                                                                                                                                                                                                                                                                  |
| `Params.tags`        | object                                                            | [Custom metric tags](/docs/k6/next/using-k6/tags-and-groups/#user-defined-tags) in key-value pairs where the keys are names of tags and the values are tag values. The WebSocket connection will [generate metrics samples](/docs/k6/next/javascript-api/k6-ws/socket/#websocket-built-in-metrics) with these tags attached, allowing users to filter the results data or set [thresholds on sub-metrics](/docs/k6/next/using-k6/thresholds/#thresholds-on-tags). |

### Example of custom metadata headers and tags

*A k6 script that makes a WebSocket request with a custom header and tags results data with a specific tag*

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

```javascript
import { WebSocket } from 'k6/websockets';

export default function () {
  const url = 'ws://localhost:10000';
  const params = {
    headers: { 'X-MyHeader': 'k6test' },
    tags: { k6test: 'yes' },
  };

  const ws = new WebSocket(url, null, params);

  ws.onopen = () => {
    console.log('WebSocket connection established!');
    ws.close();
  };
}
```

The preceding example uses a WebSocket echo server, which you can run with the following command:

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

```bash
docker run --detach --rm --name ws-echo-server -p 10000:8080 jmalloc/echo-server
```