看到这个小提琴（实际上更新了您的）
您需要钩住
componentDidMount在render方法之后要运行的对象。在那里，您可以获得元素的实际高度。
var DivSize = React.createClass({ getInitialState() { return { state: 0 }; }, componentDidMount() { const height = document.getElementById('container').clientHeight; this.setState({ height }); }, render: function() { return ( <div className="test"> Size: <b>{this.state.height}px</b> but it should be 18px after the render </div> ); }});ReactDOM.render( <DivSize />, document.getElementById('container'));<script src="https://facebook.github.io/react/js/jsfiddle-integration-babel.js"></script><div id="container"><p>jnknwqkjnkj<br>jhiwhiw (this is 36px height)</p> <!-- This element's contents will be replaced with your component. --></div>
