问题
I recently asked How to extend multiple elements with Polymer and it turned out, in fact, you can't really. The idea was to create a web component that can be applied to different elements to "decorate" them.
Addy Osmani answered this question with a few approaches to handle that use case.
One of them was:
The alternative (if you strictly want to do this all in one custom element, which imo, makes this less clean) is to do something like checking against the type of element being extended, which could either be done in the manner you linked to or by checking as part of your element registration process.
Despite from fact that this approach might be less clean, my question is:
How I can find out what element is going to be extended while I'm registering my own?
来源：https://stackoverflow.com/questions/24179075/how-to-find-out-what-element-is-going-to-be-extended-while-registering-my-own-i