React基础巩固(五)——基础案例

基础案例一：电影列表

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>电影列表</title>
  </head>
  <body>
    <div id="root"></div>

    <script
      crossorigin
      src="https://unpkg.com/react@18/umd/react.development.js"
    ></script>
    <script
      crossorigin
      src="https://unpkg.com/react-dom@18/umd/react-dom.development.js"
    ></script>
    <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>

    <script type="text/babel">
      // 1.创建root
      const root = ReactDOM.createRoot(document.querySelector("#root"));

      // 2.封装App组件
      class App extends React.Component {
        // 组件数据
        constructor() {
          super();

          this.state = {
            movies: [
              "星际穿越",
              "流浪地球",
              "独行月球",
              "大话西游",
              "火星救援",
            ],
          };
        }

        // 渲染内容
        render() {
          // 1.对movies进行for循环
          //   const liEls = [];
          //   for (let i = 0; i < this.state.movies.length; i++) {
          //     const movie = this.state.movies[i];
          //     const liEl = <li>{movie}</li>;
          //     liEls.push(liEl);
          //   }

          //   2.movies数组 => liEls数组
          //   const liEls = this.state.movies.map((movie) => {
          //     return <li>{movie}</li>;
          //   });

          //   3.直接map
          return (
            <div>
              <h2>电影列表</h2>
              <ul>
                {this.state.movies.map((movie) => (
                  <li>{movie}</li>
                ))}
              </ul>
            </div>
          );
        }
      }

      // 3.渲染组件
      root.render(<App />);
    </script>
  </body>
</html>

基础案例二：计数器

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>计数器</title>
  </head>
  <body>
    <div id="root"></div>

    <script
      crossorigin
      src="https://unpkg.com/react@18/umd/react.development.js"
    ></script>
    <script
      crossorigin
      src="https://unpkg.com/react-dom@18/umd/react-dom.development.js"
    ></script>
    <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>

    <script type="text/babel">
      // 1.创建root
      const root = ReactDOM.createRoot(document.querySelector("#root"));

      // 2.封装App组件
      class App extends React.Component {
        // 组件数据
        constructor() {
          super();

          this.state = {
            counter: 100,
          };

          this.increment = this.increment.bind(this);
          this.decrement = this.decrement.bind(this);
        }

        // 组件方法(实例方法)
        // 加1
        increment() {
          this.setState({
            counter: this.state.counter + 1,
          });
        }

        // 减1
        decrement() {
          this.setState({
            counter: this.state.counter - 1,
          });
        }

        // 渲染内容
        render() {
          const { counter } = this.state;

          return (
            <div>
              <h2>当前计数：{counter}</h2>
              <button onClick={this.decrement}>-1</button>
              <button onClick={this.increment}>+1</button>
            </div>
          );
        }
      }

      // 3.渲染组件
      root.render(<App />);
    </script>
  </body>
</html>