Comment utiliser le sous-composant vue pour transmettre des données au composant parent

nbsp;html>


  <meta>
  <meta>
  <meta>
  <title>子组件将数据传递给父组件</title>
  <script></script>

<script>
//定义一个组件
Vue.component(&#39;counter&#39;, {
 template: &#39;\
    <p style="background:#eee;width: 238px;">\
        <p>这里是子组件里面的内容！\
        <p style="margin-top:20px">\
        <p>\
          <span style="margin-right:20px;display:inline-block;">加法运算<button @click="incrementCounter">+\
        \
        <p>\
          <span style="margin-right:20px;margin-top:20px;display:inline-block;">减法运算<button @click="deleteCounter">-\
        \
    \
  &#39;,
 data: function () {
  return {
   counter: 0
  }
 },
 methods: {
  incrementCounter: function () {
   this.counter += 1;
   this.$emit(&#39;increment&#39;,1);
  },
  deleteCounter: function () {
   this.counter -= 1;
   this.$emit(&#39;increment&#39;,2);
  }
 }
})
//执行一个组件
window.onload = function(){
  var app = new Vue({
    el: &#39;#app&#39;,
    data: {
      total: 0
    },
    methods:{
      incrementTotal: function (val) {
        if(val==1){
          this.total += 1;
        }else{
          if(this.total<=0){
            this.total = 0;
          }else{
            this.total -= 1;
          }
        }
      }
    }
  })
}
</script>

  <p>
    </p><p>这里是父组件里面的内容！</p>    
    <p>子组件传递的值：<b>{{ total }}</b></p>
    <counter></counter>