Hi Stefan,

To clarify, the Node.js Client Library version 7.0.7 is compatible with Server version 6.1.0 (since 6.0.2 actually).
The problem is that Server version 6.1.0 doesn't support javascript strict mode for its own behavior.

I confirm that exist a patch for the Lightstreamer server 6.1.0 that supports javascript strict mode and so allow to use the Node.js Client Library version 7.0.7 successfully in 'strict mode'.
However, there is no a plan for public release of this patch, but can be requested by customers at support@lightstreamer.com.

Regards,
Giuseppe