Update Arrays in node.js on disconnection in socket.io - node.js

Question

I am trying to create a new socket.io real time analytic connection. I have two types of users. Normal users and their drivers.
Here is the code for authorization
io.configure(function()
{
io.set('authorization', function(handshake, callback)
{
var userId = handshakeData.query.userId;
var type = handshakeData.query.type;
var accessKey = handshakeData.query.accessKey;
var query = "";
if(type = '')
query = 'SELECT * FROM users WHERE id = ' + userId + ' AND accessKey = ' + accessKey;
else
query = 'SELECT * FROM drivers WHERE id = ' + userId + ' AND accessKey = ' + accessKey;
db.query(query)
.on('result', function(data)
{
if(data)
{
if(type == '')
{
var index = users.indexOf(userId);
if (index != -1)
{
users.push(userId)
}
}
else
{
var index = drivers.indexOf(userId);
if (index != -1)
{
drivers.push(userId)
}
}
}
else
{
socket.emit('failedAuthentication', "Unable to authenticate");
}
})
.on('end', function(){
socket.emit('failedAuthentication', "Unable to authenticate");
})
});
});
For disconnection i have this
socket.on('disconnect', function()
{
});
i want to remove the very userId i added on disconnect. How would i do that. can i append anything to socket or what should i do?

Answer 1

If you're just trying to remove the userId from your users and drivers arrays, you can do this:
socket.on('disconnect', function() {
// remove userId from users and drivers arrays
var index;
index = users.indexOf(userId);
if (index !== -1) {
users.splice(index, 1);
}
index = drivers.indexOf(userId);
if (index !== -1) {
drivers.splice(index, 1);
}
});
Or, you can DRY it up a bit:
function removeItem(array, item) {
var index = array.indexOf(item);
if (index !== -1) {
array.splice(index, 1);
}
}
socket.on('disconnect', function() {
removeItem(users, userId);
removeItem(drivers, userId);
});
This code assumes that you put this in the same closure where the userId variable is present. If you are not doing that, then you will probably need to put the userId as a property on the socket object so that it is accessible when you need it. You don't show the larger context of how your code is organized or where this event handler is located so we can't make a more specific recommendation without seeing that.