仍然很难简单地运行简单的 react 应用程序(只是客户端来玩)。
构建正常(你可以看到配置here, previous question)
当我运行服务器时 - 客户端出现错误:
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)
这是代码:
index.js
var React = require('react');
var ReactDOM = require('react-dom');
var App = require('./components/App.js');
ReactDOM.render(
<App />,
document.getElementById('app')
);
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>
);
}
}
仅供引用:
答案是正确的，但也是一件事。
不要忘记更改 import 上的所有 require，如下所示(在 index.js 中):
import React from 'react';
import ReactDOM from 'react-dom';
import App from './components/App.js';
最佳答案
它准确地告诉您问题是什么:
You likely forgot to export your component from the file it's defined in.
更改 App.js 类似于:
// ...
export default class App extends React.Component {
// ...
顺便说一句，为什么在 index.js 中使用 require 并在 App.js 中使用 ES6 导入？
关于javascript - React.createElement : type is invalid in simple empty app，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/45320450/