[Feature] allow complex key

[tjmoses]

[Feature] allow complex key

[tjmoses]

Since this library is dealing with State, only comparison of keys within the object should ever be considered whether that's with natural, surrogate, or composite keys. I implemented basic keys within strings (natural and surrogate), but do think composite keys would be nice. Additional checks would be introducing side-effects, and limiting those is best.

I don't think a matcher function is beneficial to everyone in the sense that most would not provide this and if they are writing a basic matcher function, they probably already know what they want to compare and won't use this library. Although, you bring up a valid point in that composite keys should be implemented.

I would be open to adding that in with an additional array argument of keys vs the single that exists. Also, from your PR using indexOf is faster than several other methods and why I used it. I mean I can make it extremely short with 100% ES6+ code, but I was concerned with performance and speed. Anyways, if you want to implement something that can take a given list of composite keys to check I'm game. Thanks for your input!

[avrahamcool]

OK. understood.