How do I invoke properties in a project built by the vue webpack template?

back-end programmer, front-end learning, the problem is very simple, don"t spray me.
my code: 

export default {
  name: "hello",
  data () {
    return {
      msg: "welcome",
      object:{
         name: "Runoob" ,
         url: "Google" ,
         slogan: "Taobao" 
      }
    }
  },
  methods:{
    doSomething: function(){
      this.msg = "welcome BeiJing"
    }
  },
  computed:{
    reversedMessage:function(){
        return this.msg.split("").reverse().join("");
    },
    site: {
      // getter
      get: function () {
        return this.name + " " + this.url
      },
      // setter
      set: function (newValue) {
        var names = newValue.split(" ")
        this.name = names[0]
        this.url = names[names.length - 1]
      }
    }
  }



};



//  setter vm.name  vm.url 
vm.site = " https://www.runoob.com";
document.write("name: " + vm.name);
document.write("<br>");
document.write("url: " + vm.url);

my error: 

HelloWorld.vue?18db:72 Uncaught ReferenceError: vm is not defined
    at eval (HelloWorld.vue?18db:72)
    at Object../node_modules/babel-loader/lib/index.js!./node_modules/vue-loader/lib/selector.js?type=script&index=0!./src/components/HelloWorld.vue (app.js:758)
    at __webpack_require__ (app.js:679)
    at fn (app.js:89)
    at eval (HelloWorld.vue?9042:1)
    at Object../src/components/HelloWorld.vue (app.js:1039)
    at __webpack_require__ (app.js:679)
    at fn (app.js:89)
    at eval (selector.js?type=script&index=0!./src/App.vue:1)
    at Object../node_modules/babel-loader/lib/index.js!./node_modules/vue-loader/lib/selector.js?type=script&index=0!./src/App.vue (app.js:750)
(anonymous) @ HelloWorld.vue?18db:72
./node_modules/babel-loader/lib/index.js!./node_modules/vue-loader/lib/selector.js?type=script&index=0!./src/components/HelloWorld.vue @ app.js:758
__webpack_require__ @ app.js:679
fn @ app.js:89
(anonymous) @ HelloWorld.vue?9042:1
./src/components/HelloWorld.vue @ app.js:1039
__webpack_require__ @ app.js:679
fn @ app.js:89
(anonymous) @ selector.js?type=script&index=0!./src/App.vue:1
./node_modules/babel-loader/lib/index.js!./node_modules/vue-loader/lib/selector.js?type=script&index=0!./src/App.vue @ app.js:750
__webpack_require__ @ app.js:679
fn @ app.js:89
(anonymous) @ App.vue?a8e9:1
./src/App.vue @ app.js:1024
__webpack_require__ @ app.js:679
fn @ app.js:89
(anonymous) @ main.js?1c90:1
./src/main.js @ app.js:1047
__webpack_require__ @ app.js:679
fn @ app.js:89
0 @ app.js:1064
__webpack_require__ @ app.js:679
(anonymous) @ app.js:725
(anonymous) @ app.js:728
vue.esm.js?efeb:8566 You are running Vue in development mode.
Make sure to turn on production mode when deploying for production.
See more tips at https://vuejs.org/guide/deployment.html
sockjs.js?3600:1605 XHR finished loading: GET "http://localhost:8080/sockjs-node/info?t=1535449391140".
Vue.js javascript node.js front-end
May.11,2021

Update: I seem to know what the problem is with the landlord.
on the one hand, the landlord wants to experience vue by manually going to vm.data . On the other hand, the webpack tool is used.

1. If you want to go to vm.data to observe data changes,

then I'm afraid you'll have to use the upstairs method instead of webpack build tool
directly let vm = new Vue (.) ;

2. I just want to use webpack , how to solve it?

then don't use the vm.data method.
execute this.data.name = "Lao Wang"

directly in the mounted method.

3. If you take a closer look at the rookie tutorial, he is also 

 let vm = new Vue(...);

4. Summary
if you are just beginning to contact and want to experience vue, then directly introduce vue.js, to the html page according to rookie tutorial / ide/instance.html" rel= "nofollow noreferrer" > vue official website tutorial

compare typing (because these tutorials are all done in this way, it is easier to use). I think it's almost combined with webpack scaffolding to watch some actual DEMO

.

vm is not defined. You have to assign vue to a variable first. 

import vm form 'vue'

each Vue application starts by creating a new Vue instance with the Vue function:
var vm = new Vue ({
/ / option
})

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3b690-2ba0b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3b690-2ba0b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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