vuejs2.0 implements the method of using $emit for event monitoring data transfer in paging components_javascript skills

var barHtml = &#39;<p class="page-bar">&#39;+
   &#39;<ul>&#39;+
   &#39;<li v-if="cur>1"><a v-on:click="cur--,pageClick()">上一页</a></li>&#39;+
   &#39;<li v-if="cur==1"><a class="banclick">上一页</a></li>&#39;+
   &#39;<li v-for="index in indexs" v-bind:class="{ active: cur == index}">&#39;+
    &#39;<a v-on:click="btnclick(index)">{{ index }}</a>&#39;+
   &#39;</li>&#39;+
   &#39;<li v-if="cur!=all"><a v-on:click="cur++,pageClick()">下一页</a></li>&#39;+
   &#39;<li v-if="cur == all"><a class="banclick">下一页</a></li>&#39;+
   &#39;<li><a>共<i>{{all}}</i>页</a></li>&#39;+
   &#39;</ul>&#39;+
  &#39;</p>&#39;;
 var navBar = Vue.extend({
 template:barHtml,
 props:[&#39;all&#39;,&#39;cur&#39;],
 computed: {
  indexs: function(){
  var left = 1;
  var right = this.all;
  var ar = [];
  if(this.all>= 5){
  if(this.cur > 3 && this.cur < this.all-2){
   left = this.cur - 2
   right = this.cur + 2
  }else{
   if(this.cur<=3){
   left = 1
   right = 5
   }else{
   right = this.all
   left = this.all -4
   }
  }
  }
  while (left <= right){
  ar.push(left)
  left ++
  }
  return ar
  } 
 },
 methods: {
  btnclick: function(data){
  if(data != this.cur){
   this.cur = data;
   this.$emit(&#39;btn-click&#39;,data); 
  }
  },
  pageClick: function(){
  this.$emit(&#39;btn-click&#39;,this.cur);
  }
 }, 
 });
 window.pagenav = navBar;

<p id="page">
 <vue-nav :cur.sync="cur" :all.sync="all" v-on:btn-click="listenDate"></vue-nav>
 <p style="margin-left:40px;">{{msg}}</p>
</p>

.page-bar{
 margin:40px;
}
ul,li{
 margin: 0px;
 padding: 0px;
}
li{
 list-style: none
}
.page-bar ul{
 overflow: hidden;
}
.page-bar li{
 float: left;
}
.page-bar li:first-child>a {
 margin-left: 0px
}
.page-bar a{
 display: block;
 border: 1px solid #ddd;
 text-decoration: none;
 position: relative;
 padding: 6px 12px;
 margin-left: -1px;
 line-height: 1.42857143;
 color: #337ab7;
 cursor: pointer
}
.page-bar a:hover{
 background-color: #eee;
}
.page-bar a.banclick{
 cursor:not-allowed;
}
.page-bar .active a{
 color: #fff;
 cursor: default;
 background-color: #337ab7;
 border-color: #337ab7;
}
.page-bar i{
 font-style:normal;
 color: #d44950;
 margin: 0px 4px;
 font-size: 12px;
}

var pageBar = new Vue({
 el: '#page',
 data: {
  all: 8, //总页数
  cur: 1,//当前页码
  msg:''
 },
 components:{
  'vue-nav':pagenav
 },
 watch: {
  cur: function(oldValue , newValue){
  console.log('监听cur前与后的值：');
  console.log(arguments);
  }
 }, 
 methods:{
  listenDate:function(data){
  this.cur = data;
  this.msg = '你点击了'+data+ '页';
  }
 }
 })

<p id="page">
 <vue-nav :cur.sync="cur" :all.sync="all" v-on:btn-click="listenDate"></vue-nav>
 <p style="margin-left:40px;">{{msg}}</p>
</p>