React JS - Uncaught TypeError：无法读取未定义

Question

我想在用户点击TopicsList组件并隐藏SingleTopicBox组件时显示SelectedTopicPage组件。但是，我在topic-list.jsx文件中收到错误：Uncaught TypeError: Cannot read property 'bind' of undefined。

主要-controller.jsx

import {React, ReactDOM} from '../../../build/react';

import TopicsList from '../topic-list.jsx';
import SelectedTopicPage from '../selected-topic-page.jsx';
import topicPages from '../../content/json/topic-pages.js';

export default class MainController extends React.Component {

  state = {
    isTopicClicked: false,
    topicPages
  };

  onClick(topicID) {
    this.setState({isTopicClicked: true});
    this.setState({topicsID: topicID});
  };

  render() {
    return (
      <div className="row">
        {this.state.isTopicClicked
          ? <SelectedTopicPage topicsID={this.state.topicsID} key={this.state.topicsID} topicPages={topicPages}/>
          : <TopicsList/>}
      </div>
    );
  }
};

主题的list.jsx

import {React, ReactDOM} from '../../build/react';

import SingleTopicBox from './single-topic-box.jsx';
import SelectedTopicPage from './selected-topic-page.jsx';
import topicPages from '../content/json/topic-pages.js';

export default class TopicsList extends React.Component {
  onClick(){
    this.props.onClick.bind(null, this.topicID);
  },
  render() {
    return (
      <div className="row topic-list">
        <SingleTopicBox topicID="1" onClick={this.onClick} label="Topic"/>
        <SingleTopicBox topicID="2" onClick={this.onClick} label="Topic"/>
        <SingleTopicBox topicID="3" onClick={this.onClick} label="Topic"/>
        <SingleTopicBox topicID="4" onClick={this.onClick} label="Topic"/>
      </div>
    );
  }
};

单主题-box.jsx

import {React, ReactDOM} from '../../build/react';

export default class SingleTopicBox extends React.Component {

    render() {
        return (
            <div>
                <div className="col-sm-2">
                    <div className="single-topic" data-topic-id={this.props.topicID}>
                        {this.props.label} {this.props.topicID}
                    </div>
                </div>
            </div>
        );
    }
};

Answer 1

你有几个错误

1. 您应该将onClick传递给TopicsList

   render() {
     return (
       <div className="row">
         {this.state.isTopicClicked
           ? <SelectedTopicPage 
                topicsID={this.state.topicsID} 
                key={this.state.topicsID} 
                topicPages={topicPages} />
           : <TopicsList onClick={ this.onClick.bind(this) } />}
       </div>
     );
   }
   

2. 从onClick

   中删除TopicsList方法

    onClick() {
      // ...
    },
   

3. 从onClick

   传递props回调

   <SingleTopicBox topicID="1" onClick={this.props.onClick} label="Topic"/>
   

4. 添加到SingleTopicBox onClick活动

   <div 
      className="single-topic" 
      data-topic-id={this.props.topicID} 
      onClick={ () => this.props.onClick(this.props.topicID) }
   >
     {this.props.label} {this.props.topicID}
   </div>
   

5. 您不需要两次致电setState

    onClick(topicID) {
      this.setState({
        isTopicClicked: true, 
        topicsID: topicID
      });
    }
   

Example