uni-app小程序开发-下拉菜单的实现

前言

uni-ui中有uni-combox组件，但是没有下拉的按钮组。

https://uniapp.dcloud.net.cn/component/uniui/uni-combox.html

我们可以自己实现一个。

自定义组件

z-drop-down-menu.vue

<template>
	<view class="z-drop-down-menu">
		<view class="z-drop-down-menu__input-box" @click="toggleSelector">
			<slot></slot>
			<uni-icons class="stat_icon" :type="showSelector ? 'top' : 'bottom'" size="14" color="#999"></uni-icons>
		</view>
		<view class="z-drop-down-menu__selector" v-if="showSelector">
			<view class="uni-popper__arrow"></view>
			<scroll-view scroll-y="true" class="z-drop-down-menu__selector-scroll">
				<view class="z-drop-down-menu__selector-empty" v-if="candidates === 0">
					<text>{{ emptyTips }}</text>
				</view>
				<view class="z-drop-down-menu__selector-item" v-for="(item, index) in candidates" :key="index" @click="onSelectorClick(index)">
					<text>{{ item }}</text>
				</view>
			</scroll-view>
		</view>
	</view>
</template>

<script>
/**
 * 下拉菜单
 * @description
 * @property {String} placeholder 输入框占位符
 * @property {Array} candidates 候选项列表
 * @property {String} emptyTips 筛选结果为空时显示的文字
 */
export default {
	name: 'z-drop-down-menu',
	emits: ['changeSelect'],
	props: {
		tag: {
			type: [Object, Number, String],
			default: null
		},
		placeholder: {
			type: String,
			default: ''
		},
		candidates: {
			type: Array,
			default() {
				return [];
			}
		},
		emptyTips: {
			type: String,
			default: '无匹配项'
		}
	},
	data() {
		return {
			compId: '',
			showSelector: false
		};
	},
	computed: {},
	watch: {},
	beforeMount() {},
	methods: {
		toggleSelector() {
			this.showSelector = !this.showSelector;
		},
		onSelectorClick(index) {
			this.showSelector = false;
			this.$emit('changeSelect', {
				opt: this.candidates[index],
				tag: this.tag
			});
		}
	}
};
</script>

<style lang="scss" scoped>
.z-drop-down-menu {
	font-size: 14px;
	padding: 6px 10px;
	position: relative;
	width: 100%;
	z-index: 999;
}

.stat_icon {
	margin-left: 10rpx;
}

.z-drop-down-menu__input-box {
	position: relative;
	display: flex;
	align-items: center;
}

.z-drop-down-menu__input-plac {
	font-size: 14px;
	color: #999;
}

.z-drop-down-menu__selector {
	/* #ifndef APP-NVUE */
	box-sizing: border-box;
	/* #endif */
	position: absolute;
	top: calc(100% + 12px);
	left: 0;
	width: 100%;
	background-color: #ffffff;
	border: 1px solid #ebeef5;
	border-radius: 6px;
	box-shadow: 0 2px 12px 0 rgba(0, 0, 0, 0.1);
	z-index: 2;
	padding: 4px 0;
}

.z-drop-down-menu__selector-scroll {
	/* #ifndef APP-NVUE */
	max-height: 200px;
	box-sizing: border-box;
	/* #endif */
}

.z-drop-down-menu__selector-empty,
.z-drop-down-menu__selector-item {
	/* #ifndef APP-NVUE */
	display: flex;
	cursor: pointer;
	/* #endif */
	line-height: 36px;
	font-size: 14px;
	text-align: center;
	// border-bottom: solid 1px #DDDDDD;
	padding: 0px 10px;
}

.z-drop-down-menu__selector-item:hover {
	background-color: #f9f9f9;
}

.z-drop-down-menu__selector-empty:last-child,
.z-drop-down-menu__selector-item:last-child {
	/* #ifndef APP-NVUE */
	border-bottom: none;
	/* #endif */
}

// picker 弹出层通用的指示小三角
.uni-popper__arrow,
.uni-popper__arrow::after {
	position: absolute;
	display: block;
	width: 0;
	height: 0;
	border-color: transparent;
	border-style: solid;
	border-width: 6px;
}

.uni-popper__arrow {
	filter: drop-shadow(0 2px 12px rgba(0, 0, 0, 0.03));
	top: -6px;
	left: 10%;
	margin-right: 3px;
	border-top-width: 0;
	border-bottom-color: #ebeef5;
}

.uni-popper__arrow::after {
	content: ' ';
	top: 1px;
	margin-left: -6px;
	border-top-width: 0;
	border-bottom-color: #fff;
}

.z-drop-down-menu__no-border {
	border: none;
}
</style>

使用

<z-drop-down-menu :candidates="options" :tag="index" @changeSelect="itemSelect">
    <view class="z_text_base">更多</view>
</z-drop-down-menu>

<script>
export default {
	data() {
		return {
			options: ['买断', '续租', '评价']
		};
	},
	methods: {
		itemSelect(item) {
			let { opt, tag } = item;
			console.info(opt);
			console.info(tag);
		}
	}
};
</script>