React根据宽度自适应高度的示例代码

class Card extends React.Component {
 constructor(props) {
 super(props);
 this.state = {
 width: props.width || -1,
 height: props.height || -1,
 }
 }

 componentDidMount() {
 this.updateSize();
 window.addEventListener('resize', () => this.updateSize());
 }

 componentWillUnmount() {
 window.removeEventListener('resize', () => this.updateSize());
 }

 updateSize() {
 try {
 const parentDom = ReactDOM.findDOMNode(this).parentNode;
 let { width, height } = this.props;
 //如果props没有指定height和width就自适应
 if (!width) {
 width = parentDom.offsetWidth;
 }
 if (!height) {
 height = width * 0.38;
 }
 this.setState({ width, height });
 } catch (ignore) {
 }
 }

 render() {
 return (
 <div className="test" style={ { width: this.state.width, height: this.state.height } }>
 {`${this.state.width} x ${this.state.height}`}
 </div>
 );
 }
}

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