Return the scroll position of the current page

Use Window.pageXOffset and Window.pageYOffset if they are defined, otherwise Element.scrollLeft and Element.scrollTop.

Omit the single argument, el, to use the global Window object.

const getScrollPosition = (el = window) => ({
  x: el.pageXOffset !== undefined ? el.pageXOffset : el.scrollLeft,
  y: el.pageYOffset !== undefined ? el.pageYOffset : el.scrollTop
});

// EXAMPLE
getScrollPosition(); // {x: 0, y: 200}

Source

https://www.30secondsofcode.org/js/s/get-scroll-position