react篇章-React Props

state 和 props 主要的区别在于 props 是不可变的，而 state 可以根据与用户交互来改变。这就是为什么有些容器组件需要定义 state 来更新和修改数据。而子组件只能通过 props 来传递数据。

demo1

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>菜鸟教程 React 实例</title>
<script src="https://cdn.staticfile.org/react/16.4.0/umd/react.development.js"></script>
<script src="https://cdn.staticfile.org/react-dom/16.4.0/umd/react-dom.development.js"></script>
<script src="https://cdn.staticfile.org/babel-standalone/6.26.0/babel.min.js"></script>
</head>
<body><div id="example"></div>
<div id = "helloReactZzw"></div>
<script type="text/babel">
function HelloMessage(props) {
    return <h1>Hello {props.name}!</h1>;
}class HelloMessageZzw extends React.Component {
  render() {
    return (
      <h1>Hello, {this.props.myname}</h1>
    );
  }
}const element = <HelloMessage name="Runoob"/>;
const elementZzw = <HelloMessageZzw myname = "zzwLearningReact"/>;//const elementZzw1 = <HelloMessageZzw myname = "zzwLearningReact"/> +  <HelloMessage name="Runoob"/>;
//留一下一个问题下次思考ReactDOM.render(
    elementZzw,
    document.getElementById('example')
);
</script></body>
</html>

demo2

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>菜鸟教程 React 实例</title>
<script src="https://cdn.staticfile.org/react/16.4.0/umd/react.development.js"></script>
<script src="https://cdn.staticfile.org/react-dom/16.4.0/umd/react-dom.development.js"></script>
<script src="https://cdn.staticfile.org/babel-standalone/6.26.0/babel.min.js"></script>
</head>
<body><div id="example"></div>
<div id = "helloZzw"/>
<script type="text/babel">
class HelloMessage extends React.Component {
  render() {
    return (
      <h1>Hello, {this.props.myname}</h1>
    );
  }
}HelloMessage.defaultProps = {
  name: 'Runoob',
  myname:'zzw',
};const element = <HelloMessage/>;ReactDOM.render(
  element,
  document.getElementById('helloZzw')
);
</script></body>
</html>

demo3

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>菜鸟教程 React 实例</title>
<script src="https://cdn.staticfile.org/react/16.4.0/umd/react.development.js"></script>
<script src="https://cdn.staticfile.org/react-dom/16.4.0/umd/react-dom.development.js"></script>
<script src="https://cdn.staticfile.org/babel-standalone/6.26.0/babel.min.js"></script>
</head>
<body><div id="example"></div>
<script type="text/babel">class WebSite extends React.Component {
  constructor() {
      super();      this.state = {
        name: "菜鸟教程",
        site: "http://www.runoob.com"
      }
    }
  render() {
    return (
      <div>
        <Name name={this.state.name} />
        <Link site={this.state.site} />
      </div>
    );
  }
}class Zzw extends React.Component {//react声明组件时，第一个字母必须大写
  constructor() {
      super();      this.state = {
        name: "我的博客",
        site: "https://www.cnblogs.com/zzzzw"
      }
    }
  render() {
    return (
      <div>
        <Zzw1 name={this.state.name} />
        <Zzw2 site={this.state.site} />
      </div>
    );
  }
}class Name extends React.Component {
  render() {
    return (
      <h1>{this.props.name}</h1>
    );
  }
}class Link extends React.Component {
  render() {
    return (
      <a href={this.props.site}>
        {this.props.site}
      </a>
    );
  }
}class Zzw1 extends React.Component {
  render() {
    return (
      <h1>{this.props.name}</h1>
    );
  }
}class Zzw2 extends React.Component {
  render() {
    return (
      <a href={this.props.site}>
        {this.props.site}
      </a>
    );
  }
}ReactDOM.render(
  <Zzw />,
  document.getElementById('example')
);
</script></body>
</html>

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