The Paho project recently made a new Javascript client available: http://git.eclipse.org/c/paho/org.eclipse.paho.mqtt.javascript.git/

The mosquitto Javascript client, mosquitto.js, is neither as functional nor as well written as the Paho client, so is being deprecated. If you are using mosquitto.js I strongly recommend that you look to the Paho client for the future. I will be carrying out minor bug fixes but no other development will take place.

There are no plans to remove the existing files.