使用rc-if-else模块

npm install --save rc-if-else

import React from 'react';
import { If } from 'rc-if-else';

class App extends React.Component {
    render() {
        return (
            <If condition={this.props.showResult}>
                Some Results
            </If>
        );
    }
}

以下是我的方法。

import React, { useState } from 'react';

function ToggleBox({ title, children }) {
  const [isOpened, setIsOpened] = useState(false);

  function toggle() {
    setIsOpened(wasOpened => !wasOpened);
  }

  return (
    <div className="box">
      <div className="boxTitle" onClick={toggle}>
        {title}
      </div>
      {isOpened && (
        <div className="boxContent">
          {children}
        </div>
      )}
    </div>
  );
}

在上面的代码中，为了实现这一点，我使用了如下代码:

{opened && <SomeElement />}

仅当opened为true时才会呈现SomeElement。它的工作原理在于JavaScript解析逻辑条件的方式:

true && true && 2; // will output 2
true && false && 2; // will output false
true && 'some string'; // will output 'some string'
opened && <SomeElement />; // will output SomeElement if `opened` is true, will output false otherwise (and false will be ignored by react during rendering)
// be careful with 'falsy' values eg
const someValue = [];
someValue.length && <SomeElement /> // will output 0, which will be rednered by react
// it'll be better to:
someValue.length > 0 && <SomeElement /> // will render nothing as we cast the value to boolean

使用这种方法而不是CSS“display: none”的原因;

While it might be 'cheaper' to hide an element with CSS - in such case 'hidden' element is still 'alive' in react world (which might make it actually way more expensive) it means that if props of the parent element (eg. <TabView>) will change - even if you see only one tab, all 5 tabs will get re-rendered the hidden element might still have some lifecycle methods running - eg. it might fetch some data from the server after every update even tho it's not visible the hidden element might crash the app if it'll receive incorrect data. It might happen as you can 'forget' about invisible nodes when updating the state you might by mistake set wrong 'display' style when making element visible - eg. some div is 'display: flex' by default, but you'll set 'display: block' by mistake with display: invisible ? 'block' : 'none' which might break the layout using someBoolean && <SomeNode /> is very simple to understand and reason about, especially if your logic related to displaying something or not gets complex in many cases, you want to 'reset' element state when it re-appears. eg. you might have a slider that you want to set to initial position every time it's shown. (if that's desired behavior to keep previous element state, even if it's hidden, which IMO is rare - I'd indeed consider using CSS if remembering this state in a different way would be complicated)

只要找到一种新的、神奇的方法来使用(useReducer)功能组件

const [state, handleChangeState] = useReducer((state) => !state, false); 改变状态

我能够使用css属性“隐藏”。不知道可能的缺点。

export default function App() {
    const [hidden, setHidden] = useState(false);
    return (
      <div>
        <button onClick={() => setHidden(!hidden)}>HIDE</button>
        <div hidden={hidden}>hidden component</div>
      </div>
    );
  }

这是一个使用虚拟DOM的好方法:

class Toggle extends React.Component {
  state = {
    show: true,
  }

  toggle = () => this.setState((currentState) => ({show: !currentState.show}));

  render() {
    return (
      <div>
        <button onClick={this.toggle}>
          toggle: {this.state.show ? 'show' : 'hide'}
        </button>    
        {this.state.show && <div>Hi there</div>}
      </div>
     );
  }
}

例子

使用React钩子:

const Toggle = () => {
  const [show, toggleShow] = React.useState(true);

  return (
    <div>
      <button
        onClick={() => toggleShow(!show)}
      >
        toggle: {show ? 'show' : 'hide'}
      </button>    
      {show && <div>Hi there</div>}
    </div>
  )
}

例子

class App extends React.Component {
  state = {
    show: true
  };

  showhide = () => {
    this.setState({ show: !this.state.show });
  };

  render() {
    return (
      <div className="App">
        {this.state.show && 
          <img src={logo} className="App-logo" alt="logo" />
        }
        <a onClick={this.showhide}>Show Hide</a>
      </div>
    );
  }
}