excerpt.md

Taken from element.getBoundingClientRect MDN documentation:

For cross-browser compatibility, use window.pageXOffset and window.pageYOffset instead of window.scrollX and window.scrollY, except use (((t = document.documentElement) || (t = document.body.parentNode)) && typeof t.ScrollLeft == 'number' ? t : document.body).ScrollLeft and (((t = document.documentElement) || (t = document.body.parentNode)) && typeof t.ScrollTop == 'number' ? t : document.body).ScrollTop when window.pageXOffset and window.pageYOffset (and window.pageXOffset and window.pageYOffset) are undefined.

Oye.