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forceUpdate只能穿透当前组件的shouldComponentUpdate(return false)，不能穿透孩子的

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司徒正美 edited this page Aug 27, 2017 · 1 revision 
<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <script type='text/javascript' src="./dist/React.js"></script>
    <!--<script src="./test/react.js"></script>
    <script src="./test/react-dom.js"></script> -->
    <script src="./lib/babel.js"></script>
    <script type='text/babel'>
window.onload = function(){
  

    class App extends React.Component {
      constructor(props) {
        super(props);
        this.state = {
          aaa: "南京"
        };
      }
      componentWillUpdate(){
          console.log('will update')
      }
      shouldComponentUpdate(){
          console.log('第一层')
        
      }
      render() {
        return (
          <div><A />{this.state.aaa}</div>
        );
      }
    }
    class A extends React.Component {
      constructor(props) {
        super(props);
        this.state = {
          aaa: "南京"
        };
      }
      shouldComponentUpdate(){
          console.log('00000')
         return false
      }
      componentWillUpdate(){
          console.log('0000')
      }
      render() {
        return (
          <div><B /></div>
        );
      }
    }

    class B extends React.Component {
      constructor(props) {
        super(props);
        this.state = {
          aaa: "南京"
        };
      }
      shouldComponentUpdate(){
         return false
      }
      componentWillUpdate(){
          console.log('1111')
      }
      render() {
        return (
          <div>bbbb</div>
        );
      }
    }
    var div = document.getElementById('example')
    var s = ReactDOM.render(<App />, div)


    setTimeout(function(){
        s.forceUpdate( function(){
            console.log('setTimeout')
        })
    },3000)
  
   
    

}
    </script>
</head>

<body>

    <div>这个默认会被清掉</div>
    <div id='example'></div>


</body>

</html>

``html

<script type='text/javascript' src="./dist/React.js"></script> <script type='text/javascript' src="./test/react.development.js"></script> <script type='text/javascript' src="./test/react-dom.development.js"></script> 
<script type='text/javascript' src="./lib/babel.js"></script>

    <pre>应该等于
       
      
    </pre>
    <h1 id='root' class="root">

    </h1>
    <script type='text/babel'>
       var container = document.getElementById("example")
        var div = container
        var PropTypes = React.PropTypes
        if(!window.ReactDOM){
          window.ReactDOM = React
        }
        var expect = function(a) {
            return {
                toBe: function(b) {
                    console.log(a,"vs", b, a === b)
                },
                toEqual(b){
                    console.log(a,"vs", b, a +""=== b+"")
                },
                toThrow(b){
                    try{
                        a()
                    }catch(e){
                        console.log(e,"vs", b, e.message +""=== b+"")
                    }
                }
            }
        }

        const Hello = ({ name }) => <h1>Hello {name}!</h1>;
        
        class ShowMyError extends React.Component {
          constructor(props) {
            super(props);
            this.state = { error: false };
          }
        
          componentDidCatch(error, info) {
              console.log(error, info)
            this.setState({ error, info });
          }
        
          render() {
            if (this.state.error) {
              return (
                <div>
                  <h1>
                    Error AGAIN: {this.state.error.toString()}
                  </h1>
                  {this.state.info &&
                    this.state.info.componentStack.split("\n").map(i => {
                      return (
                        <div key={i}>
                          {i}
                        </div>
                      );
                    })}
                </div>
              );
            }
            return this.props.children;
          }
        }
        
        class Broken extends React.Component {
          constructor(props) {
            super(props);
            this.state = { throw: false, count: 0 };
          }
        
          render() {
            if (this.state.throw) {
              throw new Error("YOLO");
            }
        
            return (
              <div>
                <button
                  onClick={e => {
                    this.setState({ throw: true });
                  }}
                >
                  button will render error.
                </button>
        
                <button onClick={e => {
                  this.setState(({ count }) => ({
                    count: count + 1
                  }));
                }}>button will not throw</button>
        
                <div>
                  {"All good here. Count: "}{this.state.count}
                </div>
              </div>
            );
          }
        }
        
        class App extends React.Component {
          render() {
            const styles = {
              fontFamily: "sans-serif",
              textAlign: "center"
            };
            return (
              <div style={styles}>
                <Hello name="ShowMyError" />
                <h2>
                  Start clicking to see some {"\u2728"}magic{"\u2728"}
                </h2>
                <ShowMyError>
                  <Broken />
                </ShowMyError>
              </div>
            );
          }
        }
        
        ReactDOM.render(<App />, document.getElementById("root"));
</script> ```
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