React not bails out in the case props not changed

[mh-alahdadian]

The funny thing is that React already does this, except a level shallower than memo. React already bails out by default if oldProps === newProps. I.e. if the props object itself is the same. This is ofc much less common to match but it's also significantly cheaper to do.

Originally posted by @sebmarkbage in #108 (comment)

Thanks for that you mentioned this point but why this sandbox not work as like you said? I checked the props in child element and they are not equal to props I send to React.createElement ! why ?

And at the last please tell us where can we find all of these rules and points to better understand what is going on behind react

[illuminist]

Because newProps.children !== oldProps.children.

Wrapping Child with React.memo will make sure that child element will stay the same as previous props given same props for the Child.

[mh-alahdadian]

Because newProps.children !== oldProps.children.

Wrapping Child with React.memo will make sure that child element will stay the same as previous props given same props for the Child.

the above example doesn't have any children props and I think props.children == undefined and is equal between multiple renders

[illuminist]

There are the children of React.Fragment(<>{children}</>).

[eddiecooro]

@mha15 I thinks that's because React creates a new prop object every time the React.createElement gets called. You can check that for yourself here
But I still don't quite understand where the oldProps === newProps check that @sebmarkbage has talked about would be useful. (maybe some internal code paths where an already existing fiber gets re-rendered?)