TS2339: Property 'value' does not exist on type 'Component<{}, {}, any>'. react renderer unit test
TS2339: Property 'value' does not exist on type 'Component<{}, {}, any>'. react renderer unit test
import React from 'react';
import { render, screen } from '@testing-library/react';
const MyComponent = () => {
const [value, setValue] = React.useState('');
const handleChange = (event: React.ChangeEvent<HTMLInputElement>) => {
setValue(event.target.value);
}
return (
<div>
<input type="text" value={value} onChange={handleChange} />
</div>
);
};
describe('MyComponent', () => {
it('renders correctly', () => {
render(<MyComponent />);
const inputElement = screen.getByLabelText('text-input');
expect(inputElement.value).toBe(''); // error TS2339: Property 'value' does not exist on type 'Component<{}, {}, any>'
});
});
This error occurs when you try to access a property that does not exist on a React component type. In this case, we are trying to access the value
property of an input element in a unit test using the screen.getByLabelText()
method provided by the @testing-library/react
package. However, the TypeScript compiler is throwing an error because it does not recognize the value
property as part of the Component<{}, {}, any>
type.
To fix this error, we need to provide a type annotation for the inputElement
variable so that TypeScript knows it is an HTMLInputElement
. We can do this by using the as
keyword and providing the type annotation in angle brackets:
const inputElement = screen.getByLabelText('text-input') as HTMLInputElement;
expect(inputElement.value).toBe('');
This will tell TypeScript that inputElement
is an HTMLInputElement
and that it has a value
property.
Alternatively, we can use the querySelector()
method to select the input element and avoid the type annotation altogether:
const inputElement = document.querySelector('input[type="text"]') as HTMLInputElement;
expect(inputElement.value).toBe('');
This will also work because the querySelector()
method returns an Element
object, which we can cast to an HTMLInputElement
using the as
keyword.