title: Meteor, get all users on a specific page
body: <p>We are building a chat application and are currently working on a system to see all the users in a given room. </p>
  
  <p>We have a Mongo Document set up with an array of <code>active_users</code> where we will <code>push</code> and <code>pull</code> user names to in order to keep track of the online users. We have come to the conclusion that realizing a user has connected to a given room is fairly simple. All we need to do is in the router, when a user accesses the page, we <code>push</code> that user's name into the document.</p>
  
  <p>Now the tricky part is realizing when that user has left that given page? Obviously jQuery isn't a reliable option, so how do we know when a user's connection to a specific page is broken?</p>