The J IDEs provide menu access to some labs, but the following describes how a lab may be run from the session.
The Labs addon is read into locale jlab. The main function is lab_jlab_ which is also defined in z.
Calling lab with a file name starts a lab and displays relevant information:
load 'labs/labs' NB. load the lab system lab '~addons/labs/labs/core/jtaste1.ijt' NB. start the lab: A Taste of J (1) ctrl+. or menu > advances (see noun labhelp) NB. info depends on IDE 1 of 95 in '~addons/labs/labs/core/jtaste1.ijt' NB. line and line count
To advance through the lab, press the appropriate shortcut key, i.e. Ctrl+'.' in JHS or Ctrl+J in Jqt, or enter: