使用 $on(eventName) 监听事件
使用 $emit(eventName) 触发事件

<div id="example">
 <parent></parent>
</div>

<script>
var childNode = {
 template: `<button @click="incrementCounter">{{ counter }}</button>`,
 data(){
  return {
   counter: 0
  }
 },
 methods:{
  incrementCounter(){
   this.counter ++;
   this.$emit('increment');
  }
 },
}
var parentNode = {
 template: `
 <div class="parent">
  <p>{{total}}</p>
  <child @increment="incrementTotal"></child>
  <child @increment="incrementTotal"></child>
 </div>
 `,
 components: {
  'child': childNode
 },
 data(){
  return {
   'total':0
  }
 },
 methods:{
  incrementTotal(){
   this.total ++;
  }
 }
};
// 创建根实例
new Vue({
 el: '#example',
 components: {
  'parent': parentNode
 }
})
</script>

<child @pass-data="getData"></child>

 this.$emit('pass-data',this.childMsg)

this.$emit('pass-data',this.childMsg)

getData(value){
   this.msg = value;
}

<div id="example">
 <parent></parent>
</div>

<script>
var childNode = {
 template: `
 <div class="child">
  <div>
   <span>子组件数据</span>
   <input v-model="childMsg" @input="data">
  </div>
  <p>{{childMsg}}</p>
 </div>
 `,
 data(){
  return{
   childMsg:''
  }
 },
 methods:{
  data(){
   this.$emit('pass-data',this.childMsg)
  }
 }
}
var parentNode = {
 template: `
 <div class="parent">
  <div>
   <span>父组件数据</span>
   <input v-model="msg">
  </div>
  <p>{{msg}}</p>
  <child @pass-data="getData"></child>
 </div>
 `,
 components: {
  'child': childNode
 },
 data(){
  return {
   'msg':'match'
  }
 },
 methods:{
  getData(value){
   this.msg = value;
  }
 }
};
// 创建根实例
new Vue({
 el: '#example',
 components: {
  'parent': parentNode
 }
})
</script>

<comp :foo.sync="bar"></comp>

<comp :foo="bar" @update:foo="val => bar = val"></comp>

this.$emit('update:foo', newValue)

<div id="example">
 <parent></parent>
</div>
<script src="https://unpkg.com/vue"></script>
<script>
var childNode = {
 template: `
 <div class="child">
  <div>子组件数据：{{childMsg}}</div>
  <input v-model="childMsg">
  <button @click=add >+1</button>
 </div>
 `,
 data(){
  return{
   childMsg: 0
  }
 },
 methods:{
  add(){
   this.childMsg++;
   this.$emit('update:foo',this.childMsg);
  }
 }
};
var parentNode = {
 template: `
 <div class="parent">
  <p>父组件数据：{{msg}}</p>
  <child :foo.sync="msg"></child>
 </div>
 `,
 components: {
  'child': childNode
 },
 data(){
  return {
   'msg':0
  }
 }
};
// 创建根实例
new Vue({
 el: '#example',
 components: {
  'parent': parentNode
 }
})
</script>