使用React手写一个对话框或模态框的方法示例

function Dialog() {  return React.createPortal( <div>Dialog contents</div>, document.body )}

class Modal extends React.Component { render() {  const {   visible,   onClose  } = this.props  return visible && ReactDOM.createPortal(<StyledModalRoot>   <div className="box">    Content    <br/>    <button onClick={onClose}>Close</button>   </div>  </StyledModalRoot>, document.body) }}class App extends React.Component { state = {  visibleModal: false } showModal = () => this.setState( { visibleModal: true } ) handleCloseModal = () => this.setState( { visibleModal: false } ) render() {  const { visibleModal } = this.state  return <div style={{padding: '20px'}}>  <button onClick={ this.showModal }>Show Modal</button>  <Modal visible={visibleModal} onClose={ this.handleCloseModal } /> </div> }}const StyledModalRoot = styled.div` position: fixed; z-index: 1001; left: 0; top: 0; display: grid; place-items: center; width: 100%; height: 100%; background: rgba( 0, 0, 0, 0.2 ); >.box {  position: relative;  display: grid;  place-items: center;  width: 80%;  height: 80%;  background: white;  border-radius: 10px;  box-shadow: 0px 3px 5px -1px rgba(0,0,0,0.2), 0px 5px 8px 0px rgba(0,0,0,0.14), 0px 1px 14px 0px rgba(0,0,0,0.12); }`