# upgradeWebSocket

**Kind:** Constant

**Source:** [`src/adapter/bun/websocket.ts`](https://github.com/honojs/hono/blob/main/src/adapter/bun/websocket.ts#L48)

**Part of:** [Adapter](subsystem-src-adapter)

## Definition

```ts
UpgradeWebSocket<any>
```

## Value

```ts
defineWebSocketHelper((c, events) => {
  const server = getBunServer<{
    upgrade<T>(
      req: Request,
      options?: {
        data: T
      }
    ): boolean
  }>(c)

  if (!server) {
    throw new TypeError('env has to include the 2nd argument of fetch.')
  }
  const upgradeResult = server.upgrade<BunWebSocketData>(c.req.raw, {
    data: {
      events,
      url: new URL(c.req.url),
      …
```