---
title: "Socket.write( data, [options] ) | Grafana k6 documentation"
description: "Send data over the TCP socket"
---

# Socket.write()

Asynchronously sends data to the remote server. Returns a Promise that resolves when the data has been written to the socket.

## Signature

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

```javascript
socket.write(data, options)
```

## Parameters

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| Parameter        | Type                  | Description                                                                                                                          |
|------------------|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------|
| data             | string \| ArrayBuffer | Data to send. Use `ArrayBuffer` for binary data                                                                                      |
| options          | object                | Optional write configuration                                                                                                         |
| options.encoding | string                | Encoding for string data: `utf8` / `utf-8` (default), `ascii`, `base64`, `base64url`, `hex`. Ignored when `data` is an `ArrayBuffer` |
| options.tags     | object                | Custom tags for this write operation’s metrics (key-value pairs)                                                                     |

## Returns

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| Type                | Description                                           |
|---------------------|-------------------------------------------------------|
| Promise<void> | Resolves when the data has been written to the socket |

## Example

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

```javascript
import { Socket } from "k6/x/tcp"

export default async function () {
  const socket = new Socket()
  const closed = new Promise((resolve) => { socket.on("close", resolve) })
  socket.on("error", (err) => { console.error("Error:", err) })

  await socket.connect(8080, "example.com")

  // Write a plain text string (utf8 by default)
  await socket.write("Hello, server!")

  // Write base64-encoded data
  await socket.write("SGVsbG8gV29ybGQ=", { encoding: "base64" })

  // Write with custom tags for metrics
  await socket.write("request payload", {
    tags: { operation: "auth-request" },
  })

  socket.destroy()
  await closed
}
```