Question: I'm trying to determine how many pixels down I've scrolled using `window.scrollY`. But this isn't supported in IE8. What is the safe, cross-browser alternative?

Answer: 
The cross-browser compatible version for `window.scrollY` is `document.documentElement.scrollTop`. Please see the 'Notes' section of this piece of [**Mozilla documentation**](https://developer.mozilla.org/en-US/docs/Web/API/window.scrollY?redirectlocale=en-US&redirectslug=DOM/window.scrollY) for a full, detailed workaround in IE8 and before.

[**As mentioned here**](http://help.dottoro.com/ljnvjiow.php), `pageYOffset` is another alternative to window.scrollY (note though that this is only IE9+ compatible). 

In regard to the link above, check **Example 4** for a fully compatible way to get the scroll position (it even accounts for zoom as @adeneo mentioned!) using `document.documentElement.scrollTop` and `document.documentElement.scrollLeft`. 

[**Here, try out the example for yourself!**](http://help.dottoro.com/external/examples/ljnvjiow/scrollTop_4.htm)
If you're using jQuery, I used $(window).scrollTop() to get the Y position in IE 8. It seemed to work.