<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <script src="https://cdn.jsdelivr.net/npm/vue"></script> <style> .box { color: rebeccapurple; } .box_width { width: 400px; height: 400px; background-color: red; border: 1px solid green; } .uli { display: flex; list-style: none; } .uli li { margin: 15px; } .uli li:hover { cursor: pointer; } .back { color: red; background-color: royalblue; } .backfalse { background-color: green; color: white; } </style> </head> <body> <div id="app"> <div :class="bindClass">{{msg}}</div> <button @click="btn('add')">增加样式</button> <button @click="btn('cutback')">减少样式</button> <ul class="uli"> <li v-for="(item,index) in arrs" :key="index" @click="ulBtn(index)" :class="[index==isBack?'back':'backfalse']"> {{item}} </li> </ul> </div> <script> new Vue({ el: "#app", data: { msg: "测试", bindClass: "", arrs: ["便签一", "便签二", "便签三"], isBack: 0, }, methods: { btn(data) { if (data == "add") { this.bindClass = "box box_width"; } else { this.bindClass = ""; } }, ulBtn(e) { this.isBack = e }, }, }); </script> </body> </html>