As off version 2+ the emit method will no longer be supported, instead use the send method, this is because emit is widely used by Primus for internal events, so this required some hacks and also an event blacklist to maintain for avoiding event collisions, for the sake of simplicity and the sake of maintainability I decided to drop the method in primus-emitter, the new method send works the same, and it removes hacks and the old event blacklist to support.
You can always go back and install the previous version if you really need to.
$ npm install primus.io@1.1.1