Handling undefined keys about hash-it HOT 2 CLOSED

I can look into this, but I'm worried it would only be possible as a breaking change. That, and potentially have performance costs, which for an edge case would not be a good trade-off.

Let me investigate a bit.

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After much thought and investigation, I believe this would not be a good change to make. It would break existing approaches, and the opinionated stance it takes on "equality" is not one that I share.

Inherently, { a: 1, b: undefined } is not the same object in value as { a: 1 }, because its own key structure is different. Object.keys({ a: 1, b: undefined }) will return ['a','b'], whereas Object.keys({ a: 1 }) will only return ['a']. The same is true of Object.values ([1, undefined] vs [1]). If both keys and values of the object are perceived as different by the spec, then the object itself is different.

As such, if you want to consider these two to be considered equal, I would apply a normalizer function prior to hashing. You can use JSON.parse(JSON.stringify(...)) if you'd like, but that also would eliminate functions and symbols. Depending on your project needs, you may want to be more targeted.

Hopefully this explanation satisfies for the time being. That said, when I do make a breaking change in the future, I'll keep this use-case in mind to see if I can satisfy it in a clean way.

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