What does this TypeScript mean with regards to useEffect? [duplicate]

Question

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?

JEEngineer · Accepted Answer · 2023-01-03 01:15:42Z

1

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);

answered Jan 3, 2023 at 1:15

JEEngineer

1648 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

What does this TypeScript mean with regards to useEffect? [duplicate]

1 Answer 1

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Linked

Related