Add a note about document.scrollingElement to readme

tremby · tremby · commit 1334f958a103 · 2016-03-18T20:07:26.000-07:00
diff --git a/README.md b/README.md
@@ -22,6 +22,20 @@ var Scrollparent = require("scrollparent");
 Scrollparent(document.getElementById("inside-a-scrolling-div")) // HTMLDivElement
 ```
 
+## Note about the root scrolling element
+
+Internally, the root scrolling element is determined in this library
+as the result of
+
+```js
+document.scrollingElement || document.htmlElement
+```
+
+This should give a usable result in most browsers today
+but if you want to ensure full support
+you should use a `document.scrollingElement` polyfill such as
+[this one](https://github.com/mathiasbynens/document.scrollingElement).
+
 ## Contributors
 
 * Ola Holmström (@olahol)
