https://codepen.io/gaearon/pen/rrpgNB?editors=1010
https://facebook.github.io/react/docs/rendering-elements.html#rendering-an-element-into-the-dom
Applications built with just React usually have a single root DOM node. If you are integrating React into an existing app, you may have as many isolated root DOM nodes as you like.
使用React构建的应用程序通常具有单个根DOM节点。如果您将React集成到现有应用程序中,则可能需要像您所需的一样多的孤立根DOM节点。
<div id="root">
<!-- This element's contents will be replaced with your component. -->
</div>
<div id="root2">
<!-- This element's contents will be replaced with your component. -->
</div>
ReactDOM.render(
<h1>Hello, world!</h1>,
document.getElementById('root')
);
ReactDOM.render(
<h1>Hello, world!</h1>,
document.getElementById('root2')
);
https://github.com/facebook/react-devtools/blob/master/README.md#the-react-tab-doesnt-show-up