An Introduction to the dart:io Library | Dart: Structured web apps:
Now that Dart is reached version 1.0,
it could be expected to get equivalent of node.js that is using Dart.
financeCoding/chat-websocket-dart @ GitHub
In fact next step is Dart in Chrome browser, and that may be soon.
Google Dart target: Chrome soon! Other browsers...someday | Internet & Media - CNET News