改成Composition API:组合式 API的代码，

<template><!-- start --><span class="span_checkbox">操作<input type="checkbox" v-model="showInput" value="操作" /></span><div class="textarea_div" v-if="showInput"><textareaclass="LiuYanBan_textarea"name="LiuYanBan_textarea"rows="1"cols="60%"placeholder="请输入留言内容"v-model="value"></textarea><button @click="sub" class="nav_btn">提交</button></div><nav><ul><sub>虽然有点乱，但也记录了很多新知识</sub><li v-for="(item, index) in msg" :key="index"><span v-if="showInput" @click="del(index)" value="删除">删除</span><span v-if="showInput" @click="edit_bianju(index)">编辑</span><span v-show="oindex == index ? true : false"><textarea v-model="value"></textarea><button @click="csu">提交</button></span>{{ index + 1 }}. {{ item }}</li></ul></nav><!-- end -->
</template>
<!-- 这里是script标签的属性，lang="ts"表示使用TypeScript，name="LiuYanBan_cs"表示该script标签的名字，
setup表示该script标签是一个setup函数，可以访问到data、methods、computed、watch等变量。 -->
<script lang="ts" name="LiuYanBan_cs" setup>
import '@/assets/input_checkbox.scss'
import { ref } from 'vue'
let showInput = ref(false)
let value = ref('')
let msg = ref(['Options API:选项式 API','Composition API:组合式 API','data:数据','methods:方法','computed:计算','watch:监视','ref:响应式','reactive:响应式','template:模板','props:属性','emit:事件','provide:提供','inject:注入','router:路由'
])
let oindex = ref(-1)
function sub() {if (value.value.trim()) {msg.value.push(value.value)value.value = ''}
}
function edit_bianju(index: number) {value.value = msg.value[index]oindex.value = index
}
function csu() {if (oindex.value === -1) {return}msg.value[oindex.value] = value.valueoindex.value = -1value.value = ''
}
function del(index: number) {msg.value.splice(index, 1)oindex.value = -1value.value = ''
}
// function del(index: number) {
//   const newArr = msg.value.slice(0, index).concat(msg.value.slice(index + 1))
//   msg.value = newArr
//   oindex.value = -1
//   value.value = ''
// }
</script>
<style lang="scss" scoped>
.span_checkbox {display: inline-block;background-color: #e6a23c;border-radius: 5px;font-size: 1.5rem;margin: 20px 0 0 0px;input[type='checkbox'] {top: 6px;}
}
sub {margin-left: 20rem;color:lightpink;
}
.textarea_div {display: inline-block;margin: 5px 0px 0px 10px;button {font-size: 1.5rem;}
}
textarea {height: 1.5rem;font-size: 20px;color: aliceblue;
}
ul {border-style: solid;border-radius: 15px;li {margin: 10px;word-wrap: break-word;span {cursor: pointer;border-style: solid;border-width: 3px;margin: 5px;border-radius: 5px;&:hover {border-width: 0;background-color: #e6a23c;color: #ff0000;}&:active {border-width: 0;color: #e9f504;background-color: #ff0000;box-shadow:inset -2px -2px 3px rgba(255, 255, 255, 0.6),inset 2px 2px 3px rgba(0, 0, 0, 0.6);}}}
}
button:active,
input:active {border-width: 0;color: #e9f504;background-color: #ff0000;box-shadow:inset -2px -2px 3px rgba(255, 255, 255, 0.6),inset 2px 2px 3px rgba(0, 0, 0, 0.6);
}
</style>

 复选框的样式

  /* 复选框样式开始 */input[type="checkbox"] {margin: 0px 10px;-webkit-appearance: none;appearance: none;width: 25px;height: 25px;position: relative;border-radius: 50%;background-color: #ff0000;background-image: linear-gradient(to top left,rgba(0, 0, 0, 0.2),rgba(0, 0, 0, 0.2) 30%,rgba(0, 0, 0, 0));box-shadow: inset 4px 4px 4px rgba(255, 255, 255, 0.6),inset -4px -4px 5px rgba(0, 0, 0, 0.6);border: 0px solid black;& :hover {background: #303745;}& :active {box-shadow: inset -2px -2px 3px rgba(255, 255, 255, 0.6),inset 2px 2px 3px rgba(0, 0, 0, 0.6);}}input[type="checkbox"]::after {content: "";width: 100%;height: 100%;border: 2px solid #e9f504;position: absolute;left: -3px;top: -3px;border-radius: 50%;/* 复选框样式开始 */}/* 设置复选框点击之后的样式*/input[type="checkbox"]:checked::after {height: 15px;width: 25px;border-top: none;border-right: none;border-radius: 0;transform: rotate(-45deg);transition: all 0.5s ease-in-out;}/* 设置复选框点击之后的样式结束*/

Options API:选项式 API 

 

<template><!-- start --><div class="row"><textareaclass="LiuYanBan_textarea"name="LiuYanBan_textarea"rows="1"cols="30%"placeholder="请输入留言内容"v-model="value"></textarea><button @click="sub">提交</button></div><nav><ul><li v-for="(item, index) in msg" :key="index"><input type="checkbox" />{{ item }}<span @click="del(index)">删除</span><span @click="edit_bianju(index)">编辑</span><span v-show="oindex == index ? true : false"><textarea v-model="value"></textarea><button @click="csu(index)">重置</button></span></li></ul></nav><!-- end -->
</template>
<script lang="ts">
export default {name: 'App',data() {return {value: '',msg:  ['Options API:选项式 API','Composition API:组合式 API','data:数据','methods:方法','computed:计算','watch:监视','ref:响应式','reactive:响应式','template:模板','props:属性','emit:事件','provide:提供','inject:注入','router:路由'
],oindex: -1}},methods: {sub() {if (this.value.trim()) {this.msg.push(this.value)this.value = ''}},del(index: number) {this.msg.splice(index, 1)},edit_bianju(index: number) {this.value = this.msg[index]this.oindex = index},csu(index: number) {this.msg[index] = this.valuethis.oindex = -1this.value = ''}}
}
</script>
<style lang="scss" scoped>
ul {background-color: cadetblue;padding: 10px;border-radius: 10px;box-shadow: 0 0 10px;/*  倒影 */-webkit-box-reflect: below 1px linear-gradient(to bottom, transparent, #f0f0f0);
}
li {display: flex;justify-content: space-between;align-items: center;
}
.LiuYanBan_textarea {width: 52%;border-radius: 5px;color: #faf9f9;text-shadow: 1px 1px 1px #000;font-size: 20px;margin-top: 15px;
}
</style>