Prevent Background Scrolling When Displaying Popup

Question

I have a form that is displayed in a popup. After loading, the background is grayed out, but the user can still scroll the background content up and down.

How do I

Answer 1

To hide the scrollbar of the body when opening the popup

document.body.style.overflow = "hidden";

and to revert back when closing the popup

document.body.style.overflow = "visible";