React.createElement：類型在簡單的空應用程序中無效

仍然很難簡單地運行簡單的反應應用程序（只是客戶端來玩）。React.createElement：類型在簡單的空應用程序中無效

打造的是OK（你可以看到配置here, previous question）

當我運行服務器 - 有對客戶端的錯誤：

Uncaught Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object. You likely forgot to export your component from the file it's defined in.

at invariant (transformed.js:304) 
at ReactCompositeComponentWrapper.instantiateReactComponent [as _instantiateReactComponent] (transformed.js:11912) 
at ReactCompositeComponentWrapper.performInitialMount (transformed.js:27510) 
at ReactCompositeComponentWrapper.mountComponent (transformed.js:27401) 
at Object.mountComponent (transformed.js:4158) 
at mountComponentIntoNode (transformed.js:12676) 
at ReactReconcileTransaction.perform (transformed.js:5756) 
at batchedMountComponentIntoNode (transformed.js:12698) 
at ReactDefaultBatchingStrategyTransaction.perform (transformed.js:5756) 
at Object.batchedUpdates (transformed.js:29031)

下面是代碼：

指數。 js

var React = require('react'); 
var ReactDOM = require('react-dom'); 
var App = require('./components/App.js'); 

ReactDOM.render(
    <App />, 
    document.getElementById('app') 
);

的index.html

<html lang="en"> 
    <head> 
     <meta charset="UTF-8"> 
     <title>test</title> 
    </head> 
    <body> 
     <div id='app'></div> 
    </body> 
</html>

App.js：

import React from 'react'; 
import ReactDOM from 'react-dom'; 
// import {render} from 'react-dom'; //didn't helped either 

class App extends React.Component { 
    render() { 
    return (
     <div> 
     <p> Hello React!</p> 
     </div> 
    ); 
    } 
}

FYI：

答案是正確的，但也有一點。不要忘記更改所有require上import，像這裏（index.js）：

import React from 'react'; 
import ReactDOM from 'react-dom'; 
import App from './components/App.js';

來源

2017-07-26 DanilGholtsman

它告訴你到底是什麼問題：

You likely forgot to export your component from the file it's defined in.

變化App.js類似於：

// ... 
export default class App extends React.Component { 
// ...

順便說一句，你爲什麼要使用在index.js中輸入require，在App.js中輸入ES6？

來源

2017-07-26 07:42:35 idmean

wellp，我真的不習慣在ES6風格寫，強迫自己做 – DanilGholtsman

thx順便說一句，我會盡量改變和檢查 – DanilGholtsman

nope，錯誤仍然存在 – DanilGholtsman

React.createElement：類型在簡單的空應用程序中無效

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