Can't type array in react state?

Question

I have an array in state

state = {
        array: [],
    };

Later I do this

method = (el): void => {
        const {array} = this.state;
        const includesEl = array.includes(el);
}

And I'm getting an error

 Argument of type 'any' is not assignable to parameter of type 'never'.

I type state interface like this

export interface State{
    array: any[],
}

Should I type the state in state declaration as well? Because I assume the error is coming from the face that I'm setting array initially to []

Any online code sample of your question? Since info may be lacked. — keikai
– keikai, Commented Feb 28, 2020 at 8:44

Vyacheslav Palamar · Accepted Answer · 2020-02-28 09:39:39Z

1

Did you try:

state: State = {
    array: []
}

answered Feb 28, 2020 at 9:39

Vyacheslav Palamar

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2 Comments

Person Over a year ago

It works! Strange because I already have it like this class Component extends React.Component<Props, State>

Vyacheslav Palamar Over a year ago

Here is what I found: This is because they work in two different ways, the 2nd generic type parameter will allow this.setState() to work correctly, because that method comes from the base class, but initializing state inside the component overrides the base implementation so you have to make sure that you tell the compiler that you're not actually doing anything different.

SuccessFollower · Accepted Answer · 2020-02-28 08:52:44Z

0

You have to write a specific type of Argument.

method = (el: `TYPE`): void => {
  ...
}

answered Feb 28, 2020 at 8:52

SuccessFollower

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Comments

joy08 · Accepted Answer · 2020-02-28 09:33:53Z

0

Add this,

method = (el: []): void => {
        const {array} = this.state;
        const includesEl = array.includes(el);
}

or may be add this to state like state = { array : any as []}

edited Feb 28, 2020 at 9:33

answered Feb 28, 2020 at 8:58

joy08

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2 Comments

Person Over a year ago

state = { array : any[]} gives 'any' only refers to a type, but is being used as a value here

joy08 Over a year ago

@Allan or use it with as any[] like Jai suggested

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