How to get the current location on the child table


I succeeded to use frappe.ui.keys.on, but I am not able to know how I can get the current location that the mouse is standing on it of the row for the child table, how I can get it?

I tried the following but it did not work (cdt and cdn was not captured):

frappe.ui.keys.on(‘f7’, function(e, frm, cdt, cdn) {


Please I need help and thanks a lot in advance.