const React = global.React;

const ReactDOM = global.ReactDOM;

class Counter extends React.unstable_AsyncComponent {

  state = {counter: 0};

  onCommit() {

    setImmediate(() => {

      this.setState(state => ({

        counter: state.counter + 1,

      }));

    });

  }

  componentDidMount() {

    this.onCommit();

  }

  componentDidUpdate() {

    this.onCommit();

  }

  render() {

    return <h1>{this.state.counter}</h1>;

  }

}

const interval = 200;

function block() {

  const endTime = performance.now() + interval;

  while (performance.now() < endTime) {}

}

setInterval(block, interval);

// Should render a counter that increments approximately every second (the

// expiration time of a low priority update).

ReactDOM.render(<Counter />, document.getElementById('root'));

block();