Vue-computed的set和get

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <div id="app">
    {{fullName}}
    {{age}}
  </div>
</body>
<script type="text/javascript" src="./vue.js"></script>
<script>
var app=new Vue({
    el:'#app',
    data:{
      firstName:'li',
      lastName:'zhao',
      age:18
    },
    computed:{
      fullName:{
        get:function(){
          return this.firstName+' '+this.lastName
        },
        set:function(value){
          var arr = value.split(' ');
          this.firstName = arr[0];
          this.lastName = arr[1];
        },
      }
    }
})
</script>
</html>