lovecoding
/
VIP32


			
				
					
						
						
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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">
        const root = ReactDOM.createRoot(document.getElementById("root"));
        function App() {
            return <Count num={2} />
        }
        class Count extends React.Component {
            constructor(props) {
                super(props);
                console.log(props,'ssss')
                this.state = {
                    count: 0
                }
                this.getAdd = this.getAdd.bind(this);
            }
            getAdd() {
                // this.setState((prevState,props)=>{}) prevState,props传入的参数 处理后需要返回值
                this.setState((prevState,props) => {
                    console.log(props);
                   return {count: prevState.count + props.num}
                })
                // this.setState({
                //     count: this.state.count + 1
                // })
            }
            render() {
                const { count } = this.state;
                return (
                    <div>
                        <h3>
                            总数是：{count}
                        </h3>
                        
                        <button onClick={this.getAdd}>+</button>
                        
                        <button>-</button>
                    </div>
                )
            }
        }
        root.render(<App/>)
    </script>
</body>
</html>