When the server reboots, the IRC does not save the usernames and the client does not prompt the user to re-enter the name, which causes the name to default to guest.

Either reprompt or find a way to temp. save the usernames!

Currently it is possible to have multiple clients connected that have the same username. This is confusing.

When refreshing really quickly, the connectedClients array isn't emptied correctly which causes the user count to be more than it actually is.

Edit: see issue #4 which is closely related to this.

Emoji's are unmissable in todays means of communication!

Unicode (UTF8) already supports the use of emoji's, but standard keyboards (non-mobile) aren't set up for this.

Find a way to put emoji's in the input box.

The current formatting is not responsive. Would be a good addition to change this!

Like in whatsapp, it is useful to see who is currently typing a message.

Tip: use $("#input").on('change', function(e){}); and emit to the server. The server should then display that you are typing for a specific amount of time, and remove it when the input hasn't pinged within that time again.

It is still possibly to have really long names or empty ones.

Currently users can send around 5 messages per second and quickly disconnect and reconnect. This is a very vulnerable spot to hackers/spammers.

This issue is closely related to issue #1 and I believe that fixing this will also fix this issue. You need to find a way to set a cooldown on users, for example by setting a timestamp in the chatbacklog and checking when the last time was a user sent a message every time a user wants to send a new message. Also, there should be a client-side cooldown to prevent server overload (savvy hackers can of course overcome this, but we don't want to make it easy for them).

Setting a cooldown on reconnections is important as well. One way to do this is to track the IP's of clients and basically doing the same as with the chat messages.

It only points to the first integration

So on refresh the user doesn't have to retype its username.

Right now before the user has entered its name, 'guest#1' shows up. This looks messy.