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司徒正美 edited this page Oct 18, 2017 · 1 revision

there are a few events which can be built synthetically based on other events, specifically:

change is almost often synthetic, composed of events like blur, focus, input, selectionchange, etc. mouseenter and mouseleave are calculated using mouseout and mouseover events beforeinput is pretty complicated, lots going on there select events depend on a few key and mouse events along with selectionchange Other than that, most other events should correspond to browser events that you can listen for. You could also potentially listen for a dependent event for these synthetic events (for example, listen to input or keydown for change events

``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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