[erwinh]

Wait so in the prop change example they are now recommending that you can update state during a component render?

[aeroaero]

Yep it can be a useful pattern, but it must be in a conditional to stop an infinite loop.

This useful guide points it out as well: https://blog.isquaredsoftware.com/2020/05/blogged-answers-a-...

[sickcodebruh]

I found this one very surprising. I’ve operated for years with the understanding that side-effects should never ever occur within the render flow. Complicated as hooks are, I dread having to explain the nuances of this particular one to other React devs.

[jannes]

Yes, and they explain it as well. Doing that leads to the component re-rendering immediately without rendering any child components.

This should be faster than useEffect which only executes after the entire render has been committed to the DOM.

[idkwhoiam]

This caught me off guard. I've never seen this pattern anywhere including popular 3rd party React libs. Therefore it doesn't feel right but their explanation makes sense.

[_thisdot]

Far as I see they aren't. They're recommending you don't use unnecessary state. From the example, if you have state for `firstName` and `lastName`, you don't need another state for `fullName`. Just calculate it during the render as `'${firstName} ${lastName}'`

[foota]

They're referring to https://react.dev/learn/you-might-not-need-an-effect#adjusti..., where they literally call setFoor in the render method.

I guess this makes sense, but it's weird after all the "never do anything stateful in render"

[foota]

Wow, that's really weird.