Chat logger

On minecraft launcher it show in game chat but stop when you leave i was wondering if you could make it so it would still show chat even if your gone.

Thank you.

You simply cannot do that, I'll tell you why. When you disconnect the connection gets disconnected also, it means that the server no longer sends minecraft data to your computer. Short words, when you stop connecting from a minecraft server the chat also stops.
You can code a client which maintains connection after disconnecting and logs everything then saves it on a text file.

You can do this if you own the server (there are plugins that log chat for you).