This is a full-fledged xterm terminal emulator, which runs right in your browser and is based on xterm.js. The emulator is connected to a TerminalHandler instance on the backend over websockets.
This event handler spawns a bash session and a pseudoterminal. It connects the master end of the pty to the emulator running in your browser and the slave end to bash. This essentially provides a fully functional terminal session for your users in the browser (a convenient alternative for an SSH session).
This terminal is fully under your control: You can write to it (and thus execute commands) and read what commands were executed by the user using the API exposed by the TerminalHandler. This enables you to pre-type or execute commands for the user and figure out what they are doing in the terminal.
Available commands: