（1）React的开发

npx create-react-app my-app

cd my-app

npm start

npx create-react-app todolist

npm i -g npx

npx create-react-app todolist

npm start

C:\Users\Jack\AppData\Roaming\npm\node_modules

解决方法
    npm config set registry https://registry.npm.taobao.org
    //检验是否成功
    npm config get registry
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    //然后再重新执行create-react-app
    create-react-app my-app

E:\react>npx create-react-app my-react

Creating a new React app in E:\react\my-react.

Installing packages. This might take a couple of minutes.
Installing react, react-dom, and react-scripts...

npm ERR! Unexpected end of JSON input while parsing near '...,"dist":{"integrity":'

npm ERR! A complete log of this run can be found in:
npm ERR!     D:\path\nodejs\node_cach

Aborting installation.
  npm install --save --save-exact --loglevel error react react-dom react-scripts has failed.

Deleting generated file... package.json
Deleting my-react/ from E:\react
Done.

npm config set registry http://registry.cnpmjs.org
然后重新 create 项目

create-react-app my-app
    ...
    Happy hacking!
//完成了...
之前用的淘宝代理

npm config set registry https://registry.npm.taobao.org

npm config set registry http://registry.cnpmjs.org

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';

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

// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers: https://bit.ly/CRA-PWA
serviceWorker.unregister();

import React from 'react';

function App() {
  return (
    <div className="App">
      hello world
    </div>
  );
}

export default App;