<!DOCTYPE html><html><head> <meta charset="UTF-8"> <title></title> <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script></head><body> <div id="app"> <p> {{ number }} </p> <p> double1: {{ double1 }} </p> <input v-model="double2"> {{ double2 }} </div></body><script> var app = new Vue({ el: '#app', data: { number: 5 }, computed: { double1() { // 当 double1 变动时才会从新执行 return this.number * 2 }, // double2() { // // 批改 input 报错，须要 setter // return this.number * 2 // }, double2: { get: function() { return this.number * 2 }, // 批改须要 setter 拦挡 set: function(v) { this.number = v / 2 } }, } })</script></html>