lovecoding
/
W250511


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./babel.min.js"></script>
    <script src="./react.development.js"></script>
    <script src="./react-dom.development.js"></script>
</head>

<body>
    <div id="root"></div>
    <script type="text/babel">
        let root = ReactDOM.createRoot(document.getElementById("root"));
        function App() {
            return (
                <Count count={5} />
            )
        }
        class Count extends React.Component {
            constructor() {
                super();
                this.state = {
                    num: 50
                }
            }
            handleAdd = () => {
                this.setState((prevState, props) => {
                    console.log(prevState, props)
                    // num:10
                    return { num: prevState.num + props.count }
                })
            }
            render() {
                let { num } = this.state;
                return (
                    <div>
                        <h1>{num}</h1>
                        <button onClick={this.handleAdd}>+</button>
                        <br />
                        <button>-</button>
                    </div>
                )
            }
        }
        root.render(<App />);
    </script>
</body>

</html>