[whatwg/dom] Why is the second parameter to MutationObserver.observe() optional? (#332)

The second parameter to MutationObserver.observe() is optional in the specification. I don't understand why we don't simply mark it as mandatory considering that it will throw a TypeError if omitted anyway.

Behavior of browser engines:
- Gecko agrees with the spec (Argument is optional but throws a TypeError when omitted)
- WebKit / Blink mark the second parameter as mandatory

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/dom/issues/332