Javascript 未捕获类型错误：超级表达式必须为null或函数，而不是react应用程序中未定义的错误
package.json看起来像Javascript 未捕获类型错误：超级表达式必须为null或函数，而不是react应用程序中未定义的错误,javascript,reactjs,Javascript,Reactjs,package.json看起来像 { "name": "react_playlist", "version": "1.0.0", "description": "All the course files for the Net Ninja React tutorial playlist on YouTube", "main": "index.js", "scripts": { "test": "echo \"Error: no test specified\" &am
{
"name": "react_playlist",
"version": "1.0.0",
"description": "All the course files for the Net Ninja React tutorial playlist on YouTube",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "npm run build",
"build": "webpack -d && webpack-dev-server --content-base src/ --inline --hot --port 1234"
},
"repository": {
"type": "git",
"url": "git+https://github.com/iamshaunjp/react-playlist.git"
},
"author": "",
"license": "ISC",
"bugs": {
"url": "https://github.com/iamshaunjp/react-playlist/issues"
},
"homepage": "https://github.com/iamshaunjp/react-playlist#readme",
"dependencies": {
"react": "^15.6.1",
"react-dom": "^15.6.1"
},
"devDependencies": {
"babel-core": "^6.26.0",
"babel-loader": "^7.1.2",
"babel-preset-es2015": "^6.24.1",
"babel-preset-react": "^6.24.1",
"webpack": "^3.5.5",
"webpack-dev-server": "^2.7.1"
}
}
{
"name": "react_playlist",
"version": "1.0.0",
"description": "All the course files for the Net Ninja React tutorial playlist on YouTube",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "npm run build",
"build": "webpack -d && webpack-dev-server --content-base src/ --inline --hot --port 1234"
},
"repository": {
"type": "git",
"url": "git+https://github.com/iamshaunjp/react-playlist.git"
},
"author": "",
"license": "ISC",
"bugs": {
"url": "https://github.com/iamshaunjp/react-playlist/issues"
},
"homepage": "https://github.com/iamshaunjp/react-playlist#readme",
"dependencies": {
"react": "^15.6.1",
"react-dom": "^15.6.1"
},
"devDependencies": {
"babel-core": "^6.26.0",
"babel-loader": "^7.1.2",
"babel-preset-es2015": "^6.24.1",
"babel-preset-react": "^6.24.1",
"webpack": "^3.5.5",
"webpack-dev-server": "^2.7.1"
}
}
null或函数，未定义
at_继承（bundle.js:20087）
在bundle.js:20090
反对。（bundle.js:20115）
在网页上需要（bundle.js:677）
在fn（bundle.js:88）
反对。（bundle.js:14155）
在网页上需要（bundle.js:677）
位于module.exports（bundle.js:723）
在bundle.js:726 这是我的index.html
<!DOCTYPE html>
<html>
<head>
<title>React</title>
</head>
<body>
<div id="xyz"></div>
<script src = "/app/bundle.js"></script>
</body>
</html>
反应
import React from 'react';
import ReactDOM from 'react-dom';
class App extends React.component{
render(){
return (
<div>
<h1>all good</h1>
</div>
)
}
}
ReactDom.render(<App />,document.getElementById('xyz'));
从“React”导入React；
从“react dom”导入react dom；
类App扩展了React.component{
render（）{
返回(
一切都好
)
}
}
ReactDom.render（，document.getElementById（'xyz'））；
React.componentReact.componentCReactDomReactDom类应用程序扩展React.component{
render（）{
返回(
一切都好
)
}
}
ReactDOM.render（，document.getElementById（'xyz'））
这是因为您使用了React.component
而不是React.component
的大写字母C
（@ShubhamKhatri）
另外，ReactDom
应该与导入中的大小写匹配，因此它应该是ReactDom
（@AndreaFalzetti）
这是您的问题：
类应用程序扩展React.component{
render（）{
返回(
一切都好
)
}
}
ReactDOM.render（，document.getElementById（'xyz'））
有一个输入错误，它应该是React。组件
大写C
看到这个问题了吗？因为扩展类@ShubhamKhatri时出错了，我相信你也在ReactDom.render
函数中添加了
，而原来它不在那里。还有，ReactDom
应该是您导入的ReactDom
。@NimrodArgov，我只是格式化了代码，没有添加任何内容。有输入错误，它应该是React.Component
和大写的C
看到这个问题了吗？因为在扩展@ShubhamKhatri类时出错了，我相信你也在ReactDom.render
函数中添加了
，而原来它不在那里。还有，根据您的导入，ReactDom
应该是ReactDom
。@NimrodArgov，我只是格式化了代码，没有添加任何内容