Ensure proper WebSocket connection lifecycle management by using once() instead of on() for cleanup operations and separating initialization from construction to avoid race conditions.
When setting up WebSocket connections, use once() for events that should only happen once, particularly for cleanup operations:
// Good: Use once() for cleanup events
ws.once('open', () => startHeartBeats());
ws.once('close', () => clearInterval(heartbeatTimer));
ws.once('close', () => clearTimeout(missedPingTimer));
// Avoid: Using on() for one-time cleanup
ws.on('close', () => clearInterval(heartbeatTimer)); // Could fire multiple times
Separate connection initialization from construction to prevent race conditions where close handlers might execute before the connection is properly registered:
// Good: Two-phase initialization
const connection = new Connection(..., onCloseHandler);
this.connections.set(clientID, connection);
connection.init(); // Now safe to close if needed
// Avoid: Initialization in constructor that might close immediately
This pattern prevents resource leaks, ensures cleanup operations execute exactly once, and avoids timing issues where connections might be closed before being properly tracked.
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