> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/microsoft/playwright/llms.txt
> Use this file to discover all available pages before exploring further.

# WebSocket

> API reference for the Playwright WebSocket class for monitoring WebSocket connections.

The WebSocket class represents WebSocket connections established by pages. WebSocket instances are emitted via the `page.on('websocket')` event.

## Methods

### url

Returns the URL of the WebSocket.

```javascript theme={null}
const url = webSocket.url();
console.log(url);
```

**Returns:** `string`

***

### isClosed

Returns whether the WebSocket has been closed.

```javascript theme={null}
if (webSocket.isClosed()) {
  console.log('WebSocket is closed');
}
```

**Returns:** `boolean`

***

### waitForEvent

Waits for a specific event to be emitted.

```javascript theme={null}
const frame = await webSocket.waitForEvent('framesent');
console.log('Frame sent:', frame.payload);
```

<ParamField path="event" type="string" required>
  Event name. Can be:

  * `framesent` - Emitted when a frame is sent
  * `framereceived` - Emitted when a frame is received
  * `close` - Emitted when the WebSocket closes
  * `socketerror` - Emitted when a socket error occurs
</ParamField>

<ParamField path="options.predicate" type="function">
  Optional predicate function to filter events.
</ParamField>

<ParamField path="options.timeout" type="number">
  Maximum time to wait in milliseconds. Defaults to 30000 (30 seconds).
</ParamField>

**Returns:** `Promise<any>`

## Events

### framesent

Emitted when a WebSocket frame is sent from the page.

```javascript theme={null}
webSocket.on('framesent', frame => {
  console.log('Sent:', frame.payload);
});
```

Event payload:

* `payload`: string | Buffer - The frame payload

***

### framereceived

Emitted when a WebSocket frame is received by the page.

```javascript theme={null}
webSocket.on('framereceived', frame => {
  console.log('Received:', frame.payload);
});
```

Event payload:

* `payload`: string | Buffer - The frame payload

***

### close

Emitted when the WebSocket is closed.

```javascript theme={null}
webSocket.on('close', () => {
  console.log('WebSocket closed');
});
```

***

### socketerror

Emitted when a socket error occurs.

```javascript theme={null}
webSocket.on('socketerror', error => {
  console.log('Socket error:', error);
});
```

## Example Usage

### Monitor WebSocket Messages

```javascript theme={null}
page.on('websocket', ws => {
  console.log('WebSocket opened:', ws.url());
  
  ws.on('framesent', frame => {
    console.log('→', frame.payload);
  });
  
  ws.on('framereceived', frame => {
    console.log('←', frame.payload);
  });
  
  ws.on('close', () => {
    console.log('WebSocket closed');
  });
});
```

### Filter WebSocket Messages

```javascript theme={null}
page.on('websocket', ws => {
  if (ws.url().includes('api.example.com')) {
    ws.on('framereceived', frame => {
      if (typeof frame.payload === 'string') {
        const data = JSON.parse(frame.payload);
        console.log('Received data:', data);
      }
    });
  }
});
```

### Wait for Specific Message

```javascript theme={null}
const ws = await page.waitForEvent('websocket', ws => 
  ws.url().includes('chat.example.com')
);

const frame = await ws.waitForEvent('framereceived', {
  predicate: frame => {
    if (typeof frame.payload === 'string') {
      return frame.payload.includes('welcome');
    }
    return false;
  }
});

console.log('Welcome message received:', frame.payload);
```

### Handle WebSocket Errors

```javascript theme={null}
page.on('websocket', ws => {
  ws.on('socketerror', error => {
    console.error('WebSocket error:', error);
  });
  
  ws.on('close', () => {
    console.log('WebSocket connection closed');
  });
});
```