Vue.directive('demo', {
 twoWay: true,
 bind: function () {
 this.handler = function () {
  this.set(this.el.innerHTML)
 }.bind(this)
 this.el.addEventListener('input', this.handler)
 },
 update: function (newValue, oldValue) {
 this.el.innerHTML = newValue || ''
 },
 unbind: function () {
 this.el.removeEventListener('input', this.handler)
 }
})

<template>
 <div contenteditable="true"
  v-html="innerText"
  @input="changeText"></div>
</template>
<script>
 export default {
 props: ['value'],
 data(){
  return {innerText:this.value}
 },
 methods:{
  changeText(){
  this.innerText = this.$el.innerHTML;
  this.$emit('input',this.innerText);
  }
 }
 }
</script>

<template>
 <div>
 <v-edit-div v-model='text'></v-edit-div>
 <span>{{text}}</span>
 </div>
</template>
<script>
 export default {
 data(){
  return {
  text:'改一下试一试',
  }
 }
 }
</script>