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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":{},
   }
  }
});

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