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How to build bulletproof react components

Jesco Wuester on April 12, 2020

Introduction React is a declarative framework. This means instead of describing what you need to change to get to the next state (which ...

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Mark Lai • Apr 13 '20

you should use functional update when the new value is referencing the old one
That's react basic

setIsToggled((prevToggle)=>!prevToggle)

Eliseu Monar dos Santos • Apr 13 '20 • Edited

Not really. As a newcomer reading the docs, you find an example where setCount(count + 1) is used instead of a callback: reactjs.org/docs/hooks-state.html#.... Even though the API Reference indeed recommends using a callback, it's not very clear why.

Jesco Wuester • Apr 14 '20

It's mostly for when the value updates extremely fast. That way even when 2 rerenders get batched together the value stays correct. I figured it wouldn't really matter for my example tho

Mark Lai • Apr 14 '20 • Edited

That's what I meant to say
When I was a junior react developer, I always told to use callback whenever the new value is referencing the old one.
And indeed, doing simple setState it doesn't matter

But as the app grows, there are 2 cases that may cause the setState incorrect

state update really fast
multiple setState is called in different places

But I still tend to use callback whenever possible, because it's hard to justify when is okay to use the value straight away when the code is complex
Also when you are doing a large refactor, you can't rethink to make sure every single setState is safe

After the release of React hooks, I see more ppl write code that has a lot of side effect, useEffect everywhere, thus I think its more important to enforce this rule, otherwise ppl may fix a lot of silly bugs

arhsim • Apr 29 '20

Completely agree. In fact, in a function component the callback setup would also not help and the callbacks should be defined using a useCallback.

Sagar • Apr 12 '20

Thanks, Jesco for the amazing article. After reading this article I realize that in our company application we've so many duplicate states. I'll try to minimize the use of states.