<div id="app"></div>

class FirstComponent extends React.Component {
  render() {
    const isGoodWord = true
    return (
      <div>
        <h1>React 小书 { isGoodWord ? <strong> is good </strong> : <strong>is not good</strong>}</h1>
      </div>
    )
  }
}

ReactDOM.render(<FirstComponent />, document.getElementById('app'))