Is _instance pointing to _ReactInternalInstance & _ReactInternalInstance pointing to _instance, expected Structure ?

[sanjay1909]

I was playing with the examples to understand the internal code flow of React's setState.
I noticed that ReactCompositeComponentWrapper Object had reference to _instance Object which in turn had reference to the same (screenshot's console) ReactCompositeComponentWrapper Object as _ReactInternalInstance. Is that an expected structure ?

[aweary]

Yes, it is intentionally a doubly linked structure. ReactCompositeComponentWrapper is an internal only and wraps user-defined composite components. It holds a reference to the instance of the user-defined component that is defined when it is mounted. Then ReactInstanceMap is used to store a reference to the internal wrapper on the public instance.

If you look at ReactInstanceMap it has some more information in the doc comments

ReactInstanceMap maintains a mapping from a public facing stateful instance (key) and the internal representation (value). This allows public methods to accept the user facing instance as an argument and map them back to internal methods.

[gaearon]

(Note these are private implementation details and will change in future versions.)

[sanjay1909]

Thanks for the clarification, it was really helpful