Portal的使用-全局组件的实现

开局先挂官方文档

https://react.docschina.org/docs/portals.html

实现全局弹出层 App.js

import React from 'react';
import './App.css';
import Mask from './Portals/Mask'
class App extends React.Component {
  constructor(props){
    super(props);
    this.state = {
      showMask:true
    }
    this.handler = this.handler.bind(this);
  }
  handler(){
    let showMask = this.state.showMask;
    this.setState({showMask:!showMask});
  }
  render() {
    let showMask = this.state.showMask;
    let mask =  showMask ?
      
        
          hidden
        
      
      : null;
    return (
      
        show
        {mask}
      
    );
  }
}
export default App;

App.css

.modal {
    color: #fff;
    background-color: rgba(0, 0, 0, 1);
    position: fixed;
    top: 0;
    left: 0;
    z-index: 999;
    height: 100%;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

Mask.jsx

import React,{Component} from 'react'
import ReactDOM from 'react-dom'
const root = document.getElementById('root');
export default class Mask extends Component{
    constructor(props){
        super(props)
        this.state={
        }
      this.el = document.createElement('div');
    }
  componentDidMount(){
    root.appendChild(this.el);
  }
  componentWillUnmount(){
    root.removeChild(this.el);
  }
    render (){
      return ReactDOM.createPortal(
        this.props.children,
        this.el
      );
    }
}

我们先看下Portals文档

ReactDOM.createPortal(child, container) 第一个参数（child）是任何可渲染的 React 子元素，例如一个元素，字符串或 fragment。 第二个参数（container）是一个 DOM 元素。

简单的理解就是，你写一个组件，将组件的内容用Portal挂载在跟节点id=root的节点，他就是全局的了

改造一下，使用起来更加方便 App.js

import React from 'react';
import './App.css';
import Mask from './Portals/Mask'
class App extends React.Component {
  constructor(props){
    super(props);
    this.state = {
      showMask:false
    }
    this.onHandler = this.onHandler.bind(this)
  }
  onHandler(){
    let showMask = this.state.showMask;
    this.setState({showMask:!showMask});
  }
  render() {
    return (
      
        show
        
      
    );
  }
}
export default App;

App.css

同上

Mask.jsx

import React,{Component} from 'react'
import ReactDOM from 'react-dom'
const root = document.getElementById('root');
export default class Mask extends Component{
    constructor(props){
        super(props)
        this.state={
        }
      this.el = document.createElement('div');
    }
  componentDidMount(){
    root.appendChild(this.el);
  }
  componentWillUnmount(){
    root.removeChild(this.el);
  }
    render (){
      return ReactDOM.createPortal(
        this.props.showMask ?
        
          this.props.onHandler()}>hidden
         : null,
        this.el
      );
    }
}