When using allowJs, you are unable to use classes that do not extend a declared class without including its generic type arguments.

[joelday]

TypeScript Version: 2.2.2

In this specific scenario, allowJs is enabled and react.d.ts is available. The React typings declares Component<P, S>. In a JavaScript file, a class is defined that extends React.Component, but without the generic arguments.

Code
foo.js:

export class FooComponent extends React.Component {
  ...
}

bar.tsx:

import { FooComponent } from './foo'

...

<FooComponent />
or
const f = new FooComponent(…)

Expected behavior:
An ES6 class from './foo' that extends React.Component without generic arguments can be used in a .tsx file that imports it.

Actual behavior:
"[ts] Cannot use 'new' with an expression whose type lacks a call or construct signature." errors.

I think that this class should be automatically inferred to have extended React.Component<any, any>

[jwbay]

Seems like #14907 might resolve this

[joelday]

Dupe of #14881