repeater filter using public.js filter ??

So rather than having an onlick button to do search off dropdowns, how does one initiate an onchange style search using public.js file?
I hate click to search and prefer an onchange, however as a newbie I am trying to use the input search box and two dropdowns. But I want the dropdowns to be dependent.

I’ve flushed out the typical menu styles using database queries and got a grasp on them, but now on to this project.

Will start with the “easy” part of just finding way to make the dropdowns alone. So set up a public.js file for each and got that in place, but question is then how to get an onchange in place for the two to function in filtering a repeater. Help in filling in my blanks???

export function iCategory_change(event, $w) {
// insert blank stare
export function iSection_change(event, $w) {
// insert blink blink