computed的setter妙用

使用场景：当我们用v-model绑定了一个计算属性，想直接设置计算属性时，就要利用到setter

demo：

<template>
  <div>
    <div>First Name:
      <el-input v-model="firstName" placeholder="请输入内容"></el-input>
    </div>
    <div>Second Name:
      <el-input v-model="secondName" placeholder="请输入内容"></el-input>
    </div>
    <div>Full Name:
      <el-input v-model="fullName" placeholder="请输入内容"></el-input>
    </div>
  </div>
</template>

export default{
  data () {
    return {
      firstName: '',
      secondName: ''
    }
  },
  components: {},
  computed: {
    fullName: {
      get: function () {
        return this.firstName + ' ' + this.secondName
      },
      set: function (newVal) {
        let names = newVal.split(' ')
        this.firstName = names[0]
        this.secondName = names[1]
      }
    }
  }
}

实现的效果：firstName 、secondName 发生变化，fullName会自动更新；反过来，fullName的改变，firstName 和 secondName也会自动更新。