A few years ago I created a page for testing browser support of different DOM properties and methods. As it was just a testing tool for a particular project I never made it publicly available. I can across it the other day and thought it may be useful to other developers here it is DOM Browser Support.
This page tests your browser for DOM (Document Object Model) support and allows you to compare it to other popular browsers. The first column after the property name shows your browser result.
The tests used are very simple and results should only be used as a guide. Be aware of browsers that only partially support the property
I managed to get cool little drop down menu working with just a couple of lines of code for a site I am developing.