我通常使用组件组合来以 React 方式重用逻辑。例如，这里有一个关于如何向组件添加交互逻辑的简化版本。在这种情况下，我会让 CanvasElement 可选:

CanvasElement.js

import React, { Component } from 'react'
import Selectable from './Selectable'
import './CanvasElement.css'

export default class CanvasElement extends Component {
  constructor(props) {
    super(props)

    this.state = {
      selected: false
    }

    this.interactionElRef = React.createRef()
  }

  onSelected = (selected) => {
    this.setState({ selected})
  }

  render() {
    return (
      <Selectable
        iElRef={this.interactionElRef}
        onSelected={this.onSelected}>

        <div ref={this.interactionElRef} className={'canvas-element ' + (this.state.selected ? 'selected' : '')}>
          Select me
        </div>

      </Selectable>
    )
  }
}

Selectable.js

import { Component } from 'react'
import PropTypes from 'prop-types'

export default class Selectable extends Component {
  static propTypes = {
    iElRef: PropTypes.shape({
      current: PropTypes.instanceOf(Element)
    }).isRequired,
    onSelected: PropTypes.func.isRequired
  }

  constructor(props) {
    super(props)

    this.state = {
      selected: false
    }
  }

  onClick = (e) => {
    const selected = !this.state.selected
    this.setState({ selected })
    this.props.onSelected(selected)
  }

  componentDidMount() {
    this.props.iElRef.current.addEventListener('click', this.onClick)
  }

  componentWillUnmount() {
    this.props.iElRef.current.removeEventListener('click', this.onClick)
  }

  render() {
    return this.props.children
  }
}

工作得很好。 Selectable 包装器不需要创建新的 div，因为它的父元素为它提供了对另一个将变为可选择的元素的引用。

但是，我曾多次被建议停止使用此类 Wrapper 组合，而是通过 Higher Order Components 实现可重用性。 .愿意尝试 HoC，我尝试了一下，但没有比这更进一步:

CanvasElement.js

import React, { Component } from 'react'
import Selectable from '../enhancers/Selectable'
import flow from 'lodash.flow'
import './CanvasElement.css'

class CanvasElement extends Component {
  constructor(props) {
    super(props)

    this.interactionElRef = React.createRef()
  }

  render() {
    return (
      <div ref={this.interactionElRef}>
        Select me
      </div>
    )
  }
}

export default flow(
  Selectable()
)(CanvasElement)

Selectable.js

import React, { Component } from 'react'

export default function makeSelectable() {
  return function decorateComponent(WrappedComponent) {
    return class Selectable extends Component {

      componentDidMount() {
        // attach to interaction element reference here
      }

      render() {
        return (
          <WrappedComponent {...this.props} />
        )
      }
    }
  }
}

问题是似乎没有明显的方法将增强组件的引用(实例变量)连接到高阶组件(增强器)。

我如何将实例变量(interactionElRef)从 CanvasElement“传递”到它的 HOC？

最佳答案

我想出了一个不同的策略。它的行为大致类似于 Redux connect 函数，提供包装组件不负责创建的 props，但 child 负责在他们认为合适的时候使用它们:

CanvasElement.js

import React, { Component } from "react";
import makeSelectable from "./Selectable";

class CanvasElement extends Component {
  constructor(props) {
    super(props);
  }

  render() {
    const { onClick, selected } = this.props;
    return <div onClick={onClick}>{`Selected: ${selected}`}</div>;
  }
}

CanvasElement.propTypes = {
  onClick: PropTypes.func,
  selected: PropTypes.bool,
};

CanvasElement.defaultProps = {
  onClick: () => {},
  selected: false,
};

export default makeSelectable()(CanvasElement);

Selectable.js

import React, { Component } from "react";

export default makeSelectable = () => WrappedComponent => {
  const selectableFactory = React.createFactory(WrappedComponent);

  return class Selectable extends Component {
    state = {
      isSelected: false
    };

    handleClick = () => {
      this.setState({
        isSelected: !this.state.isSelected
      });
    };

    render() {
      return selectableFactory({
        ...this.props,
        onClick: this.handleClick,
        selected: this.state.isSelected
      });
    }
  }
};

https://codesandbox.io/s/7zwwxw5y41

我知道这不能回答您的问题。我认为您是想让 child 在 parent 不知情的情况下离开。

不过，ref 路由感觉不对。我喜欢将工具与 child 联系起来的想法。您可以在其中任何一个中响应点击。

让我知道你的想法。

关于javascript - 如何将实例变量从 React 组件传递给它的 HOC？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/50401485/