help.tsx

// entry point
import * as React from 'react';
import * as ReactDOM from 'react-dom';
import { asMap, observable, useStrict } from 'mobx';
import { Provider } from 'mobx-react';

import { App } from './components/App';

useStrict(true);

const store = observable(asMap({}));

ReactDOM.render(
    <Provider store={store}>
        <App />
    </Provider>,
    document.getElementById('app')
);

// App.tsx
import * as React from 'react';
import { action, observable } from 'mobx';
import { inject, observer } from 'mobx-react';
import DevTools from 'mobx-react-devtools';

@inject('store') // i think this is correct?
@observer
export class App extends React.Component<??????, {}> {
    render() {
        return (
            <div>
                <h1>
                    App
                </h1>
                <DevTools />
            </div>
        );
    }
}