react return里返回多个元素值要有父标签包裹。

React.Fragment组件能够在不额外创建 DOM 元素的情况下，让 render()方法中返回多个元素。相当于空标签<></>。

<></>包裹多个元素↓：

import React, { Component, Fragment } from "react";
import "./App.css";

class App extends Component {
  render() {
    return (
      <>
        <div>
          <input />
          <button>按钮</button>
        </div>
        <ul>
          <li>哈</li>
          <li>咯</li>
        </ul>
      </>
    );
  }
}

export default App;

 使用Fragment标签↓：

和<></>实现效果一致。

import React, { Component, Fragment } from "react";
import "./App.css";

class App extends Component {
  render() {
    return (
      <Fragment>
        <div>
          <input />
          <button>按钮</button>
        </div>
        <ul>
          <li>哈</li>
          <li>咯</li>
        </ul>
      </Fragment>
    );
  }
}

export default App;

 <React.Fragment>就不用在头部引入了↓：

import React, { Component } from "react";
import "./App.css";

class App extends Component {
  render() {
    return (
      <React.Fragment>
        <div>
          <input />
          <button>按钮</button>
        </div>
        <ul>
          <li>哈</li>
          <li>咯</li>
        </ul>
      </React.Fragment>
    );
  }
}

export default App;

 使用<div>包裹多个标签就会多一层嵌套↓：

 

import React, { Component, Fragment } from "react";
import "./App.css";

class App extends Component {
  render() {
    return (
      <div>
        <div>
          <input />
          <button>按钮</button>
        </div>
        <ul>
          <li>哈</li>
          <li>咯</li>
        </ul>
      </div>
    );
  }
}

export default App;

<></>和Fragment标签的区别

Fragment标签支持能接受键值或属性，可以遍历循环渲染元素

import React, { Component } from "react";
import "./App.css";

const list = [
  { id: 0, name: "凤凰火", description: "最肉" },
  { id: 1, name: "彼岸花", description: "花花" },
];
class App extends Component {
  render() {
    return list.map((item) => (
      <React.Fragment key={item.id}>
        <li>
          {item.name}是{item.description}
        </li>
      </React.Fragment>
    ));
  }
}

export default App;