Cross-browser method for detecting the scrollTop of the browser window

Question

What is the best cross-browser way to detect the scrollTop of the browser window? I prefer not to use any pre-built code libraries because this is a very simple script, and

Answer 1

I know its been quite a while since this thread was updated, but this is a function I created that allows developers to find the root element that actually hosts has a working "scrollTop" property. Tested on Chrome 42 and Firefox 37 for Mac OS X (10.9.5):

function getScrollRoot(){
    var html = document.documentElement, body = document.body,
        cacheTop = ((typeof window.pageYOffset !== "undefined") ? window.pageYOffset : null) || body.scrollTop || html.scrollTop, // cache the window's current scroll position
        root;

    html.scrollTop = body.scrollTop = cacheTop + (cacheTop > 0) ? -1 : 1;
    // find root by checking which scrollTop has a value larger than the cache.
    root = (html.scrollTop !== cacheTop) ? html : body;

    root.scrollTop = cacheTop; // restore the window's scroll position to cached value

    return root; // return the scrolling root element
}

// USAGE: when page is ready: create a global variable that calls this function.

var scrollRoot = getScrollRoot();

scrollRoot.scrollTop = 10; // set the scroll position to 10 pixels from the top
scrollRoot.scrollTop = 0; // set the scroll position to the top of the window

I hope you find this useful! Cheers.