My current project requires me to use Mutation Observers, and I couldn’t resist the temptation to do a little fundamental research. Overall they work fine, but there is one tricky bit when it comes to text changes. Also, I found two Edge bugs.
My current client asked me to keep track of DOM nodes that appear onmouseover — and my script should work in pretty much any site. So we have add some information to DOM nodes that appear onmouseover, which will allow a later script to figure out that there was a mouseover involved. That’s obviously a job for Mutation Observers.