How to prevent child component from re-rendering when using React hooks and memo?

In your case it doesn’t really makes sense to memoize Child because if item changes, the child has to re-render. However if there is a case that props do not change , but still the child is re-rendering due to the functions getting recreated you would make use of useCallback hook to memoize the functions, on each render. Also since you have memoized the handler, you should make use of the callback method to update state since item inside the handler will only refer to the value it had when the function was initially created

function Parent() {
  const [item, setItem] = useState({ name: "item", value: 0 });

  const handleChangeItem = useCallback(() => {
    setItem(prevItem => ({ ...prevItem, value: prevItem.value + 1 }));
  }, []);

  return (
    <>
      Name: {item.name} Value: {item.value}
      <Child changeItem={handleChangeItem} />
    </>
  );
}

const Child = React.memo(function Child({ item, changeItem }) {
  function handleClick() {
    changeItem();
  }
  console.log("child render");
  return (
    <div>
      <button onClick={handleClick}>change state in parent</button>
    </div>
  );
});

Working demo

P.S. Credit to @danAbramov for the direction