Yes, as in this is the endpoint (Julian was talking about) : node-red-nodes/25-serial.js at 5c333db0ddb445442a998452e7c55e89b81e08da · node-red/node-red-nodes · GitHub
that is called from the client side like this: node-red-nodes/25-serial.html at 5c333db0ddb445442a998452e7c55e89b81e08da · node-red/node-red-nodes · GitHub