react-条件渲染

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我是靠谱客的博主能干便当，最近开发中收集的这篇文章主要介绍react-条件渲染，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

静态条件渲染

示例代码：

<!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>Document</title>
    <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
    <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
    <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
    <style>
        .h1 {
            color: red;
        }

        .div1 {
            width: 100px;
            height: 100px;
            background-color: pink;
        }
    </style>
</head>

<body>
    <!-- react的容器 -->
    <div id="app"></div>
</body>

</html>
<script type="text/babel">
    class ComClass extends React.Component {
        constructor() {
            super();
            //静态的条件渲染(注意:只能取消this.state = { a: xxx }进行演示)
            this.state = { a: 1 }
            // this.state = { a: 2 }
            // this.state = { a: 3 }
        }
        render() {
            //当this.state.a不同会渲染出对应的组件,静态条件渲染
            if (this.state.a == 1) {
                return <div>内容1</div>
            } else if (this.state.a == 2) {
                return <div>内容2</div>
            } else {
                return <div>内容3</div>
            }
        }
    }
    //不同的条件去return不同东西，达到渲染不同的东西，这就是条件渲染
    ReactDOM.render(<ComClass />, document.querySelector("#app"));
</script>

动态条件渲染

示例代码：

<!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>Document</title>
    <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
    <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
    <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
    <style>
        .h1 {
            color: red;
        }

        .div1 {
            width: 100px;
            height: 100px;
            background-color: pink;
        }
    </style>
</head>

<body>
    <!-- react的容器 -->
    <div id="app"></div>
</body>

</html>
<script type="text/babel">
    class ComClass extends React.Component {
        constructor() {
            super();
            this.state = {
                a: 1
            }
        }
        render() {
            let com;
            //动态的条件渲染
            //条件判断完，com会等于不同的东西,下面的{com}就会展示不同的div
            if (this.state.a == 1) {
                com = <div>内容1</div>
            } else if (this.state.a == 2) {
                com = <div>内容2</div>
            } else {
                com = <div>内容3</div>
            }
            return (
                <div>
                    <button onClick={() => { this.setState({ a: 1 }) }}>按钮1</button>
                    <button onClick={() => { this.setState({ a: 2 }) }}>按钮2</button>
                    <button onClick={() => { this.setState({ a: 3 }) }}>按钮3</button>
                    {com}
                </div>
            )
        }
    }
    //不同的条件去return不同东西，达到渲染不同的东西，这就是条件渲染
    ReactDOM.render(<ComClass />, document.querySelector("#app"));
</script>