Merge pull request reduxjs#1 from extrange/extrange-patch-1

Update part-5-ui-and-react.md

Author: extrange

docs/tutorials/fundamentals/part-5-ui-and-react.md

@@ -497,7 +497,7 @@ const TodoListItem = ({ id }) => {
 export default TodoListItem
 ```
 
-There's a problem with this, though. We said earlier that **returning new array references in selectors causes components to re-render every time**, and right now we're returning a new IDs array in `<TodoListItem>`. In this case, the _contents_ of the IDs array should be the same if we're toggling a todo, because we're still showing the same todo items - we haven't added or deleted any. But, the array _containing_ those IDs is a new reference, so `<TodoList>` will re-render when it really doesn't need to.
+There's a problem with this, though. We said earlier that **returning new array references in selectors causes components to re-render every time**, and right now we're returning a new IDs array in `<TodoList>`. In this case, the _contents_ of the IDs array should be the same if we're toggling a todo, because we're still showing the same todo items - we haven't added or deleted any. But, the array _containing_ those IDs is a new reference, so `<TodoList>` will re-render when it really doesn't need to.
 
 One possible solution to this is to change how `useSelector` compares its values to see if they've changed. `useSelector` can take a comparison function as its second argument. A comparison function is called with the old and new values, and returns `true` if they're considered the same. If they're the same, `useSelector` won't make the component re-render.