1、创建启动react项目：

npx create-react-app 项目名        //创建
npm install                       //安装依赖
npm start                         //启动

2、跨域代理：

【1】文档：https://create-react-app.dev/docs/proxying-api-requests-in-development/

npm install http-proxy-middleware --save

【2】src/setupProxy.js:

const { createProxyMiddleware } = require('http-proxy-middleware');

module.exports = function(app) {
  app.use(
    '/ajax',
    createProxyMiddleware({
      target: 'https://m.maoyan.com',
      changeOrigin: true,
    })
  );
  app.use(
    '/api',
    createProxyMiddleware({
      target: 'https://i.maoyan.com',
      changeOrigin: true,
    })
  );
};