javascript - 在我的组件中 react 不变违规错误

Question

我正在学习 ReactJS，并在尝试将 Youtube API 数据渲染到组件中时，我偶然发现了以下警告和错误。我试图了解它们背​​后的原因，但我对发生的事情一无所知。

Warning: React.createElement: type should not be null, undefined, boolean, or number. It should be a string (for DOM elements) or a ReactClass (for composite components). Check the render method of App.

Uncaught Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object. Check the render method of App.

Warning: React.createElement: type should not be null, undefined, boolean, or number. It should be a string (for DOM elements) or a ReactClass (for composite components). Check the render method of App.

Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object. Check the render method of App.

Uncaught TypeError: Cannot read property 'props' of undefined

我正在使用的有问题的代码如下。我确信这与我的 App 组件以及我如何设置 props 对象有关，但我无法查明问题的根源。

index.js

import React, {Component} from 'react';
import ReactDOM from 'react-dom';
import SearchBar from './components/search_bar';
import YTSearch from 'youtube-api-search';
import VideoList from './components/video_list';

const API_KEY = "not showing the real key here for obvious reasons"; 

class App extends Component {
    constructor(props){
        super(props);

        this.state = {videos: []};

        YTSearch({key: API_KEY, term: 'sufboards'}, (videos) => { 
            this.setState({videos});
        });
    }
    render(){
        return (
            <div>
                <SearchBar />
                <VideoList videos={this.state.videos} />
            </div>
        );
    }
}
ReactDOM.render(<App />, document.querySelector(".container"));

video_detail.js

import React from 'react';

const VideoList = (props) => {
    return (
        <ul className="col-md-4 list-group">
            {props.videos.length}
        </ul>
    );
};

export default VideoList;

search_bar.js

import React, {Component} from 'react';

class SearchBar extends Component {
    constructor(props){
        super(props);
        this.state = {term: ""};
    }

    render(){
        return (
            <input
                onChange={
                    event => this.setState({
                        term: event.target.value
                    })
                }
                value = {this.state.term}
            />
        );
    }
}

export default SearchBar;

Answer 1

简单修复:

从“./components/video_list”导入VideoList；

该文件为空，我的代码位于 video_detail.js 中，因此我必须将其移动到正确的文件 video_list.js