> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stacyos.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Example App: TypeScript Code Runner

> Build an Express application that runs JavaScript code inside disposable StacyVM sandboxes with the TypeScript SDK.

This example uses the TypeScript SDK to build a small HTTP API. Each request gets a fresh sandbox, writes submitted code to `/app/main.js`, runs it with Node.js, returns the result, and destroys the sandbox.

## Prerequisites

* Node.js 18+.
* A running StacyVM server.
* Docker provider access on the StacyVM host.
* A StacyVM API key if auth is enabled.

The source lives in [`examples/code-runner-typescript`](https://github.com/StacyOS/stacyvm/tree/main/examples/code-runner-typescript).

## Install

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
cd examples/code-runner-typescript
npm install
```

## Configure

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
export STACYVM_URL="http://localhost:7423"
export STACYVM_API_KEY="sk_test_YOUR_API_KEY"
export STACYVM_IMAGE="node:20"
```

## Run The App

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
npm run dev
```

## Submit Code

<CodeGroup>
  ```bash cURL theme={"theme":{"light":"github-light","dark":"github-dark"}}
  curl -sS -X POST http://localhost:8081/run-javascript \
    -H "Content-Type: application/json" \
    -d '{"code":"console.log([10, 20, 12].reduce((a, b) => a + b, 0));","timeout":"10s"}'
  ```

  ```javascript JavaScript theme={"theme":{"light":"github-light","dark":"github-dark"}}
  const response = await fetch("http://localhost:8081/run-javascript", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      code: "console.log([10, 20, 12].reduce((a, b) => a + b, 0));",
      timeout: "10s",
    }),
  });

  if (!response.ok) {
    throw new Error(await response.text());
  }

  console.log(await response.json());
  ```

  ```python Python theme={"theme":{"light":"github-light","dark":"github-dark"}}
  import requests

  response = requests.post(
      "http://localhost:8081/run-javascript",
      json={
          "code": "console.log([10, 20, 12].reduce((a, b) => a + b, 0));",
          "timeout": "10s",
      },
      timeout=30,
  )
  response.raise_for_status()
  print(response.json())
  ```
</CodeGroup>

## Response

```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
{
  "exit_code": 0,
  "stdout": "42\n",
  "stderr": "",
  "duration": "120ms"
}
```

## Production Notes

Before exposing this service, add authentication, request size limits, per-user quota attribution, audit logging, and host runtime certification.

## Related

* [TypeScript SDK](/docs/sdks/typescript)
* [REST sandboxes](/docs/rest/sandboxes)
* [System architecture](/docs/architecture/system-overview)