abort

I’m making some long polling with node.js.
Basically, node.js server accepts request from the user and then checks for some updates. If there’re no updates, it will check them after the timeout.
But what if user has closed his tab, or went to another page? In my case, the script continues working.
Is there a way in node.js to check or detect or to catch an event when user has aborted his request (closed the connection)?