In that case, is there a more legit way of checking like seeing if it has any unique properties?

Isn't o['data'] instanceof FormData enough on its own? Why is the typeof check neccesary?

@keronsen In older browsers, FormData is not defined, so o['data'] instanceof FormData will throw ReferenceError.

Any updates on this? According to @yeonhoyoon's last comment, perhaps the check should be:

typeof FormData !== 'undefined', or 'FormData' in window