1、安装​​http-proxy-middleware​​

$ npm install http-proxy-middleware --save
$ # or
$ yarn add http-proxy-middleware

2、创建一个​​setupProxy.js​​​文件，在src目录，​​src/setupProxy.js​​

例如之前的配置

"proxy": {
  "/api": {
    "target": "http://localhost: 3000/"
    }
}

setupProxy.js文件里则这样写

const proxy = require('http-proxy-middleware')
 
module.exports = function(app) {
  app.use(proxy('/api', { target: 'http://localhost: 3000/' }))
}

完整的写法

app.use(proxy('/api', { 
target: 'https://localhost: 3000/',
changeOrigin:true,
pathRewrite: {
            "^/api": "/"
        }
}))