4 ms·
I'm not sure why you think it wouldn't. Any time a component renders, React also renders all of its children except the ones for which shouldComponentUpdate ret
by RussianCow 7y ago
I'm not sure why you think it wouldn't. Any time a component renders, React also renders all of its children except the ones for which shouldComponentUpdate returns false. If that is defined by using PureComponent or React.memo on a child, then you have to make sure that the props you pass in are not going to change on every re-render (i.e. you can't pass an un-memoized callback because a new function reference will be created on every render).
I've created a CodePen to illustrate: https://codepen.io/RussianCow/pen/xxbERLL https://codepen.io/RussianCow/pen/xxbERLL
Open the console and watch as the "render child" message is logged once per second, showing that the child is re-rendered every time the parent is.