Access to XMLHttpRequest at 'http://localhost:8080/xxx' from origin 'http://localhost:8080' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

 Due to browser same-origin policy restrictions. The Same Origin Policy is a convention. This is the main and essential security feature of the browser. Without the same-origin policy, normal browser functionality may be affected. The web is built on the same-origin policy, and browsers are just one implementation of the same-origin policy. The Same Origin Policy prevents JavaScript scripts from one domain from interacting with content from another domain. The so-called same origin (that is, the same domain) means that two pages have the same protocol, host and port.

Solution: 

1. Set the response header on the server side

res.setHeader("Access-Control-Allow-Origin","*")

2. Use third-party middleware such as cors

import cors from "cors"

app.use(cors())

3. Configure the proxy

//vue.config.js

devServer:{

    port:8088,

    proxy:"http://localhost:6060"

  }

//App,vue

methods:{

      getInfo(){

        axios.get("http://localhost:8088/info").then(

          response=>{

            console.log("success-666!!!")

            console.log(response.data)

          },

          err=>{

            console.log(err.message)

          }

        )

      }

    }

4. Configure multiple proxies

  devServer:{

   port:8088,

   proxy:{

        "/hello":{

          target:"http://localhost:6060",

          changeOrigin:true,

          pathRewrite:{"^/hello":""}

        },

        // "/xxx":{},

   }

  }

});