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@@ -0,0 +1,58 @@
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+<!DOCTYPE html>
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+<html lang="en">
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+
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+<head>
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+ <meta charset="UTF-8">
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+ <meta name="viewport" content="width=device-width, initial-scale=1.0">
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+ <title>Document</title>
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+ <script src="./babel.min.js"></script>
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+ <script src="./react.development.js"></script>
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+ <script src="./react-dom.development.js"></script>
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+</head>
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+
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+<body>
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+ <div id="root"></div>
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+ <script type="text/babel">
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+ const root = ReactDOM.createRoot(document.getElementById("root"));
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+ function App() {
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+ return (
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+ <div>
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+ <Count num={5} />
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+ </div>
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+ )
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+ }
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+ class Count extends React.Component {
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+ constructor(props) {
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+ super(props);
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+ this.state = {
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+ count: 0
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+ }
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+ }
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+ handleAdd() {
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+ // this.setState({
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+ // count: this.state.count + 1
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+ // })
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+ this.setState((prevState, props) => {
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+ console.log(prevState, props, '打印1')
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+ return {
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+ count: prevState.count + props.num
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+ }
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+ })
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+ }
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+ render() {
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+ return (
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+ <div>
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+ <p>
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+ <button onClick={this.handleAdd.bind(this)}>+</button>
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+ {this.state.count}
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+ <button>-</button>
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+ </p>
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+ </div>
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+ )
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+ }
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+ }
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+ root.render(<App />);
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+ </script>
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+</body>
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+
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+</html>
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郑柏铃