React根據寬度自適應高度實例分享

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

ReactDOM.render(
 <Card/>,
 document.getElementById(&#39;root&#39;)
);