ReactJS-销毁旧的组件实例并创建新的 [英] ReactJS - Destroy old Component-Instance and create new

问题描述

我有一个可能令人困惑的问题，因为它不符合标准行为，如何反应以及虚拟dom的工作原理，但我还是想知道答案。

I've got a may confusing question because it does not fit standard-behaviour how react and the virtual dom works but i would like to know the answer anyway.

想象一下，我有一个简单的反应组件，称为容器。
容器组件在渲染方法内部有一个 div，其中包含另一个名为 ChildContainer的组件。包围 ChildContainer的 div具有id wrappingDiv。

Imagine i've got a simple react-component which is called "Container". The Container-component has a "div" inside of the render-method which contains another component called "ChildContainer". The "div" which surrounds the "ChildContainer" has the id "wrappingDiv".

示例：

render() {
  <Container>
    <div id="wrappingDiv">
      <ChildContainer/>
    </div>
  </Container
}

我如何销毁 ChildContainer -component-instance并创建一个全新的组件。这意味着将调用旧实例的 ComponentWillUnmount，并调用新组件的 ComponentDidMount。

How can i destroy the "ChildContainer"-component-instance and create a completly new one. Which mean the "ComponentWillUnmount" of the old instance is called and the "ComponentDidMount" of the new component is called.

我不希望通过更改状态或道具来更新旧组件。

I don't want the old component to update by changing the state or props.

我需要这个行为，因为我们合作伙伴公司的外部库获得了一个可更改dom项目的库，并且在React中，当我更新组件时，我将收到找不到节点异常。

I need this behaviour, because an external library from our partner-company got a libary which change the dom-items and in React i'll get a "Node not found" exception when i Update the component.

推荐答案

如果为组件提供密钥，然后更改该密钥重新渲染时，旧的组件实例将被卸载，而新的实例将被装载：

If you give the component a key, and change that key when re-rendering, the old component instance will unmount and the new one will mount:

render() {
  ++this.childKey;
  return <Container>
    <div id="wrappingDiv">
      <ChildContainer key={this.childKey}/>
    </div>
  </Container>;
}

孩子将有一个新的钥匙

The child will have a new key each time, so React will assume it's part of a list and throw away the old one, creating the new one. Any state change in your component that causes it to re-render will force that unmount-and-recreated behavior on the child.

实时示例：

class Container extends React.Component {
  render() {
    return <div>{this.props.children}</div>;
  }
}

class ChildContainer extends React.Component {
  render() {
    return <div>The child container</div>;
  }
  componentDidMount() {
    console.log("componentDidMount");
  }
  componentWillUnmount() {
    console.log("componentWillUnmount");
  }
}

class Example extends React.Component {
  constructor(...args) {
    super(...args);
    this.childKey = 0;
    this.state = {
      something: true
    };
  }

  componentDidMount() {
    let timer = setInterval(() => {
      this.setState(({something}) => ({something: !something}));
    }, 1000);
    setTimeout(() => {
      clearInterval(timer);
      timer = 0;
    }, 10000);
  }
  
  render() {
    ++this.childKey;
    return <Container>
      {this.state.something}
      <div id="wrappingDiv">
        <ChildContainer key={this.childKey}/>
      </div>
    </Container>;
  }
}

ReactDOM.render(
  <Example />,
  document.getElementById("root")
);

<div id="root"></div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.4.2/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.4.2/umd/react-dom.production.min.js"></script>

话虽如此，对于您的插件潜在问题，可能会有更好的答案。但以上内容解决了实际提出的问题...：-）

Having said that, there may well be a better answer to your underlying issue with the plugin. But the above addresses the question actually asked... :-)

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