How can you reset a component's internal state from the parent?
Quick answer
Change its key prop. A new key makes React treat it as a brand-new element, unmounting the old one and remounting fresh.
In detail
Because reconciliation matches elements by type and key, changing the key forces React to discard the old instance (and its state) and create a new one. This is the idiomatic way to reset a form or component when a meaningful identifier changes, without manually clearing every field.
// remount (clear all internal state) when the user changes
<ProfileForm key={userId} user={user} />Why interviewers ask this: A clever question that tests deep reconciliation understanding.
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