### getScrollPosition

Returns the scroll position of the current page.

Use `pageXOffset` and `pageYOffset` if they are defined, otherwise `scrollLeft` and `scrollTop`.
You can omit `el` to use a default value of `window`.

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

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