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I am new to TypeScript and am learning it by setting up a new project and how I would normally do that, but with TypeScript along the way. I have this bit of React working but do not know what this means -- therefore which document I should be reading to learn up on it.

const [user, setUser] = useState<any | null>(false);

Specifically the <any | null> part. This is the only new part with TypeScript but not sure how to read this. Is this saying the type is any type, else null? What are some other options I can use in place of any and null? Are there scenarios I should avoid?

mattie_g
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1 Answers1

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That's the correct way to type a useState but normally you want to avoid using any.

In your example you are creating some state with a default value of false. In this case you don't really need to define the type as it will be inferred as a boolean. Let's say that value could be null or an object, then you could define the type like so:

// Just an example
interface User {
  username: string
}

const [user, setUser] = useState<User | null>(null);
JEEngineer
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