数量选择组件-基本结构
（1）准备基本结构
<script lang="ts" setup name="Numbox">//</script><template> <div class="numbox"> <div class="label">数量</div> <div class="numbox"> <a href="javascript:;">-</a> <input type="text" readonly value="1" /> <a href="javascript:;">+</a> </div> </div></template><style scoped lang="less">.numbox { display: flex; align-items: center; .label { width: 60px; color: #999; padding-left: 10px; } .numbox { width: 120px; height: 30px; border: 1px solid #e4e4e4; display: flex; > a { width: 29px; line-height: 28px; text-align: center; background: #f8f8f8; font-size: 16px; color: #666; &:first-of-type { border-right: 1px solid #e4e4e4; } &:last-of-type { border-left: 1px solid #e4e4e4; } } > input { width: 60px; padding: 0 5px; text-align: center; color: #666; } }}</style>（2）全局注册
import Numbox from '@/components/numbox/index.vue'export default { install(app: App) { app.component('Numbox', Numbox) },}（3）提供类型声明
import Numbox from '@/components/numbox/index.vue'declare module 'vue' { export interface GlobalComponents { Numbox: typeof Numbox }}export {}（4）渲染
<div class="spec"> <!-- 数字选择框 --> <XtxNumbox></XtxNumbox></div>效果
数量选择组件-v-model语法糖
目标：掌握vue3.0的v-model语法糖原理
在vue2.0中v-mode语法糖简写的代码
在vue3.0中v-model语法糖有所调整：
演示代码：
<script lang="ts" setup>defineProps({ money: { type: Number, default: 0, },})const emit = defineEmits(['update:money'])</script><template> <h3>子组件-{{ money }}</h3> <button @click="emit('update:money', money + 1)">+1</button></template><style scoped lang="less"></style>总结： vue3.0封装组件支持v-model的时候，父传子:modelValue 子传父 @update:modelValue
补充： vue2.0的 xxx.sync 语法糖解析 父传子 :xxx 子传父 @update:xxx 在vue3.0 使用 v-model:xxx 代替。
数量选择组件-功能实现
大致功能分析：
- 默认值为1
- 可限制最大最小值
- 点击-就是减1 点击+就是加1
- 需要完成v-model得实现
- 存在无label情况
<script lang="ts" setup name="Numbox">const props = defineProps({ modelValue: { type: Number, default: 1, }, min: { type: Number, default: 1, }, max: { type: Number, default: 20, }, showLabel: { type: Boolean, default: false, },})const emit = defineEmits<{ (e: 'update:modelValue', value: number): void}>()const add = () => { if (props.modelValue >= props.max) return emit('update:modelValue', props.modelValue + 1)}const sub = () => { if (props.modelValue <= props.min) return emit('update:modelValue', props.modelValue - 1)}</script><template> <div class="numbox"> <div class="label" v-if="showLabel"><slot>数量</slot></div> <div class="numbox"> <a href="javascript:;" @click="sub">-</a> <input type="text" readonly :value="modelValue"/> <a href="javascript:;" @click="add">+</a> </div> </div></template><style scoped lang="less">.numbox { display: flex; align-items: center; .label { width: 60px; color: #999; padding-left: 10px; } .numbox { width: 120px; height: 30px; border: 1px solid #e4e4e4; display: flex; > a { width: 29px; line-height: 28px; text-align: center; background: #f8f8f8; font-size: 16px; color: #666; &:first-of-type { border-right: 1px solid #e4e4e4; } &:last-of-type { border-left: 1px solid #e4e4e4; } } > input { width: 60px; padding: 0 5px; text-align: center; color: #666; } }}</style>动态控制禁用效果
<script lang="ts" setup name="Numbox">const props = defineProps({ modelValue: { type: Number, default: 1, }, min: { type: Number, default: 1, }, max: { type: Number, default: 20, }, showLabel: { type: Boolean, default: false, },})const emit = defineEmits<{ (e: 'update:modelValue', value: number): void}>()const add = () => { if (props.modelValue >= props.max) return emit('update:modelValue', props.modelValue + 1)}const sub = () => { if (props.modelValue <= props.min) return emit('update:modelValue', props.modelValue - 1)}</script><template> <div class="numbox"> <div class="label" v-if="showLabel"><slot>数量</slot></div> <div class="numbox"> + <a href="javascript:;" @click="sub" :class="{not:props.modelValue <= props.main}">-</a> <input type="text" readonly :value="modelValue" /> + <a href="javascript:;" @click="add" :class="{not:props.modelValue >= props.max}">+</a> </div> </div></template><style scoped lang="less">.numbox { display: flex; align-items: center; .label { width: 60px; color: #999; padding-left: 10px; } .numbox { width: 120px; height: 30px; border: 1px solid #e4e4e4; display: flex; > a { width: 29px; line-height: 28px; text-align: center; background: #f8f8f8; font-size: 16px; color: #666; + &.not { + cursor: not-allowed; + } &:first-of-type { border-right: 1px solid #e4e4e4; } &:last-of-type { border-left: 1px solid #e4e4e4; } } > input { width: 60px; padding: 0 5px; text-align: center; color: #666; } }}</style>使用组件：src/views/goods/index.vue
<script lang="ts" setup name="Numbox">import {ref} from "vue"; const count = ref(1)</script><!-- 商品信息 --><div class="goods-info"> <!-- 数字选择框 --> <XtxNumbox v-model="count" min:"1" :max="20" ></XtxNumbox></div>思考：
我们的输入框不仅能点击加减还可以输入数字，如果用户通过输入框输入非数字会出现什么问题” />
优化代码
<script lang="ts" setup name="Numbox">const props = defineProps({ modelValue: { type: Number, default: 1, }, min: { type: Number, default: 1, }, max: { type: Number, default: 20, }, showLabel: { type: Boolean, default: false, },})+const { proxy } = getCurrentInstance() as ComponentInternalInstanceconst emit = defineEmits<{ (e: 'update:modelValue', value: number): void}>()const add = () => { if (props.modelValue >= props.max) return emit('update:modelValue', props.modelValue + 1)}const sub = () => { if (props.modelValue <= props.min) return emit('update:modelValue', props.modelValue - 1)} +const handleChange = (e: Event) => {+ // 通过类型断言，让ts知道目前元素的类型+ const element = e.target as HTMLInputElement+ let value = +element.value+ if (isNaN(value)) value = 1+ if (value >= props.max) value = props.max+ if (value <= props.main) value = props.main+ emit('update:modelValue',value) + // 强制刷新+ proxy?.$forceUpdate()} </script><template> <div class="numbox"> <div class="label" v-if="showLabel"><slot>数量</slot></div> <div class="numbox"> <a href="javascript:;" @click="sub" :class="{not:props.modelValue <= props.main}">-</a> <input type="text" readonly :value="modelValue" @change="handleChange($event)"/> <a href="javascript:;" @click="add" :class="{not:props.modelValue >= props.max}">+</a> </div> </div></template><style scoped lang="less">.numbox { display: flex; align-items: center; .label { width: 60px; color: #999; padding-left: 10px; } .numbox { width: 120px; height: 30px; border: 1px solid #e4e4e4; display: flex; > a { width: 29px; line-height: 28px; text-align: center; background: #f8f8f8; font-size: 16px; color: #666; &.not { cursor: not-allowed; } &:first-of-type { border-right: 1px solid #e4e4e4; } &:last-of-type { border-left: 1px solid #e4e4e4; } } > input { width: 60px; padding: 0 5px; text-align: center; color: #666; } }}</style>