it only updates the components that actually are affected by a state difference
Depends on what you mean by "update" here.
Yes, React only modifies the DOM if your component's render output changes.
However, React always re-renders components recursively by default, even if the props and state haven't changed. It's a very common misconception that React automatically skips rendering if the props are the same - that's an optimization you have to apply.
Depends on what you mean by "update" here.
Yes, React only modifies the DOM if your component's render output changes.
However, React always re-renders components recursively by default, even if the props and state haven't changed. It's a very common misconception that React automatically skips rendering if the props are the same - that's an optimization you have to apply.
See my post A (Mostly) Complete Guide to React Rendering Behavior for details.