Webhook Sink

The webhook sink POSTs session data as JSON to any URL. It’s the most universal sink — works with any backend that accepts HTTP requests.

Setup

import { WriteTrack, webhook } from 'writetrack';

const tracker = new WriteTrack({ target: textarea });

tracker.pipe(
  webhook({
    url: 'https://api.example.com/writetrack',
  })
);

tracker.start();

When getData() is called, the sink sends a POST request with Content-Type: application/json and the full WriteTrackDataSchema as the body.

Options

Option	Type	Default	Description
url	string	—	URL to POST session data to Required
headers	Record<string, string>	{}	Additional headers to include
retries	number	0	Number of retries on failure
keepalive	boolean	false	Use fetch keepalive so delivery completes after page close (64 KB body limit)

Examples

With Authentication

tracker.pipe(
  webhook({
    url: 'https://api.example.com/writetrack',
    headers: {
      Authorization: 'Bearer sk_live_...',
    },
  })
);

With Retries

tracker.pipe(
  webhook({
    url: 'https://api.example.com/writetrack',
    retries: 2, // up to 3 total attempts
  })
);

Retries fire immediately on non-2xx responses. The sink throws after all attempts are exhausted.

Server-Side Handler

The webhook delivers the full WriteTrackDataSchema object. Here’s a minimal Express handler:

app.post('/writetrack', (req, res) => {
  const data = req.body;

  console.log('Session from:', data.metadata.userId);
  console.log('Quality:', data.quality.qualityLevel);
  console.log('Duration:', data.metadata.duration, 'ms');
  console.log('Keystrokes:', data.session.events.length);

  // Store or process the session data
  db.sessions.insert(data);

  res.sendStatus(200);
});

Error Handling

tracker.on('pipe:error', (err, sink) => {
  console.error('Webhook delivery failed:', err.message);
  // e.g. "Webhook failed: 500 Internal Server Error"
});

Request Format

The webhook sends:

• Method: POST
• Content-Type: application/json
• Body: The complete WriteTrackDataSchema object (see Data Schema)

A non-2xx response is treated as a failure and triggers retries (if configured) or a pipe:error event.