<div id="app">
 <navbar ></navbar>
 <pagefooter ></pagefooter>
 </div>

 Vue.component('navbar',{
 template:'<div>{{navs}}</div>',
 data:function () {
 return {
 navs:1
 }
 }
 });
 Vue.component('pagefooter',{
 template:'<div>{{footer}}</div>',
 data:function () {
 return {
 footer:11
 }
 }
 });

 <div id="app">
 <navbar ref="navbar"></navbar>
 <pagefooter ref="pagefooter"></pagefooter>
 </div>
 new Vue({
 el:'#app',
 created:function(){
 
 },
 mounted:function () {
 this.$refs.navbar.navs=222
 //ready,
 //這里怎么直接訪問navbar的navs和pagefooter的footer值呢，
 console.log(this.$refs.navbar.navs);
 console.log(this.$refs.pagefooter.footer);
 }
 })

<div ref="demo"></div>

document.querySelector('[ref=demo]');