In react fiber, is didReceiveUpdate related to dirty checking? about react

[AnuragKacham]

The 1st condition directly relates to the usage of dirty checking, but the other two do not. But, they work in the same way after detecting a change. (Change of context in the component or change of the component in total). So, it is not totally related to dirty checking but it uses dirty checking as a small part.

Hope it helped!

[rickhanlonii]

Dirty checking is used to determine which individual pieces of state have changed, and then process those updates (so the diff happens first, then the update). React doesn't do dirty checking because it re-renders everything, and then compares the output with the previous output (so the update happens first, then the diff).

While this looks like dirty checking, because it's diffing the props/context, it's not really the same thing. This check is just used to bailout of the "re-render everything" process once we reach child in the tree that couldn't have changed, as a perf optimization, not the mechanism to track updates.

In other words, the flag is not used to determine what to update, but what didn't update.