Question

I’m building a Node.js / Socket.io project.

I have a hash of Users based on their websocket id. When a user makes the following request i’d like to add them to a group of users viewing that page.

app.get('/board/:id', function(req, res){}

I’d like to keep something like

Browsing = {
username : id,
username : id,
…
}

However i’m unsure how to remove a user lets say if they navigate off the page. Is there some kind of function that gets called upon page leave?

Partial Solution:

The following seems to do the trick on Chrome:

   $(window).unload(function(){
      var username = $('#username').text();
      var pid = currentProject;

      var data = {
        username: username,
        id : pid
      }

      socket.emit('leaving-page', data);
    })

Answer 1

… Is there some kind of function that gets called upon page
leave? …

Yes, but it is not reliable.

The way the people keep track of who is online and who isn’t, is usually like this:

• Add the time when the user last refreshed/visited a page
• set a limit to you consider them offline