React HOC状态出错

Question

I write a reagent nose on the basis of https://gist.github.com/jesperorb/ad6de7532ade111ae2a7feecc1116339

App.js

import React, { Component } from "react";
import {withToggle} from './withToggle'

export default class App extends Component {
  render() {
    const ButtonWithToggle = withToggle(<button onClick={()=>{}}>butt</button>);
    return (
      <div className="App">
        <button onClick={()=>{}}>butt</button>
        <ButtonWithToggle />
      </div>
    );
  }
}

withToggle.js:

import React, { Component } from "react";
import PropTypes from 'prop-types';

export const withToggle = (ComposedComponent) =>
    class extends Component {

        static propTypes = {
            children: PropTypes.string
        }

        state = {
            toggle: false
        }
        onClick = () => {
            this.setState({ toggle: !this.state.toggle });
        }

        render() {
            return (
                <ComposedComponent {...this.props} onClick={this.onClick}>xxx {this.props.children}</ComposedComponent>
            )
        }
    }

As a result, I get an error in the console: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: object. Check your code at withToggle.js:20. (Where <ComposedComponent )

What could be the reason?

Answer 1

HOC should be applied on a Component and not a rendered component.
On your case withToggle is applied on <button onClick={()=>{}}>butt</button> , which is a rendering of a button and not a button component.
Also, you're not using children right and you're overriding the onClick provided from withToggle with onClick={()=>{}} .

Try this instead:

App.js

import React, { Component } from "react";
import {withToggle} from './withToggle'

const Button = ({onClick, children}) => <button onClick={onClick}>{children}</button>;

export default class App extends Component {
  render() {
    const ButtonWithToggle = withToggle(Button);

    return (
      <div className="App">
        <button onClick={()=>{}}>butt</button>
        <ButtonWithToggle />
      </div>
    );
  }
}

withToggle.js

import React, { Component } from "react";
import PropTypes from 'prop-types';

export const withToggle = (ComposedComponent) =>
    class extends Component {

        static propTypes = {
            children: PropTypes.string
        }

        state = {
            toggle: false
        }

        onClick = () => {
            this.setState(state => ({ toggle: !state.toggle }));
        }

        render() {
            return (
                <ComposedComponent {...this.props} onClick={this.onClick}>{this.props.children}</ComposedComponent>
            )
        }
    }

Answer 2

I change withToggle.js:

import React, { Component } from "react";
import PropTypes from 'prop-types';

export const withToggle = (ComposedComponent) =>
class extends Component {

    static propTypes = {
        children: PropTypes.string.isRequired,
        onClick: PropTypes.func
    }

    static defaultProps = {
        onClick: () => { }
    }

    state = {
        toggle: false
    }
    onClick = () => {
        this.setState({ toggle: !this.state.toggle }, () => console.log('toggle=', this.state.toggle));
        this.props.onClick()
    }

    render() {
        console.log('this.props', this.props)
        return (
            <ComposedComponent {...this.props} onClick={this.onClick}>{this.state.toggle ? 'xxx' : ''}{' '}{this.props.children}</ComposedComponent>
        )
    }
}

but onClick is not redefined and the text inside the button does not change((