On: JSON Patch – a format for describing changes to a ...

[logn]

I think they used null for deletion because undefined isn't in the JSON spec. It's more of a Javascript standard.

[drderidder → logn]

Thanks, you're right. "null" is what I do use - I forgot undefined won't work with JSON.parse. It would be nice to have a way to explicitly define a property as null, versus non-extant.