Show/Hide a button on page when scrolling >200px from the top

[J.D]

You should add an anchor to the page (make it global) and place it 200px from the top.
Then -

//masterPage.js
$w.onReady(() => {
$w('#anchor1').onViewportLeave(()=> {
	$w('#buttonScrolltop').show();
})
$w('#anchor1').onViewportEnter(()=> {
	$w('#buttonScrolltop').hide();
})
})