Classic App - how to immediately assign a table keyboard focus on app load

Hi
A simple classic app - a table, and a data area that shows detail of the table's selected row.
Aim: immediately after app load, user can use keyboard navigation (principally up and down arrows for previous/next row selection with no prior interaction needed.
Issue: user is obliged to click a row in the table to give it keyboard focus. I want to avoid this necessity.
Steps I've taken: searched through here, looked for and failed to find "OnLoaded" events I can attach JS to on the table or (preferably) on the app.

Thank you.