FAQ: The Effect Hook - Rules of Hooks

This community-built FAQ covers the “Rules of Hooks” exercise from the lesson “The Effect Hook”.

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This exercise can be found in the following Codecademy content:

Learn React

FAQs on the exercise Rules of Hooks

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This exercise is misleading. You can follow the steps as written and pass the checkpoints, but the code will not render anything to the preview.
After comparing with the solution, line by line, I found you need to set the initial state for items to an empty object. This is not mentioned anywhere in the instructions. The instructions only say about setting initial state for categories and selectedCategories. This caused a lot of frustration searching for a mistake that was never there - just simply poor instructions.

const [items, setItems] = useState({});

This lesson says that hooks should not be written inside nested functions but in the previous exercise we used stateSetter() inside the useEffect(). So is it good practice to write like this?

I understood that you can only use useState() on a top level, but once you called it, it’s okay to use part of what it returns , a.k.a. setState() inside of useEffect().

But I may be wrong.


yes, you are right, useState() is the hook so you need to use it on the top, but setState() isn’t a hook so you can use it anywhere except in the return cause it will cause an infinite loop in this case.


Made it through the first 55% of the full-stack course and enjoyed it. The hooks instructions have been difficult to understand for me though. I’ll get lost and then review the solution. Once I know the answer I try to implement the same thing, but still get a failed checkpoint. I’ve even gone so far as trying to copy and paste the solution and it rejects it whenever I input it. I’m confused as to what the instructions are looking for at this point. Specifically having difficulty with step 1 vagueness on Rules of Hooks

Perhaps you can copy/paste the code you are trying OR post a screenshot. That might offer a clue as to why you can’t progress. It may also offer clues as to what is causing you confusion.