uniapp —— 实现左右联动商品分类页面
uniapp —— 实现左右联动商品分类页面
零、前因
我们在日常的开发种，这种页面在项目当中经常会用得到，所以本篇文章会比较注重描述其思路，顺带附上其代码，以便以后在任何代码环境下都能使用上，先介绍一下实现思路：
- 点击左侧类别，右侧会跳转到对应的分类；
- 右侧滚动到顶部区域，左侧自动高亮对应的类别。
要求就这么多，可以先看下效果如何：
一、搭建结构
重点：使用uniapp的scroll-view组件，如果是小程序原生开发也是这个组件；其次如果是html开发，就自己实现一个溢出滚动。
废话不多说，上代码：
<template>
<view class="u-wrap">
<view class="u-menu-wrap">
<scroll-view scroll-y scroll-with-animation class="u-tab-view menu-scroll-view" :scroll-top="scrollTop"
:scroll-into-view="itemId">
<view v-for="(item,index) in tabbar" :key="index" class="u-tab-item" :class="[current == index ? 'u-tab-item-active' : '']"
@tap.stop="swichMenu(index)">
<text class="u-line-1">{{item.name}}text>
view>
scroll-view>
<scroll-view :scroll-top="scrollRightTop" scroll-y scroll-with-animation class="right-box" @scroll="rightScroll">
<view class="page-view">
<view class="class-item" :id="'item' + index" v-for="(item , index) in tabbar" :key="index">
<view class="item-title">
<text>{{item.name}}text>
view>
<view class="item-container">
<view class="thumb-box" v-for="(item1, index1) in item.foods" :key="index1" @click="featureC(item1.cat, item1.name)">
<image v-if="item1.icon != ''" class="item-menu-image" :src="item1.icon" mode="">image>
<view v-else class="item-menu-image row-c" style="background-color: #F4F6F8;"><text style="font-size: 20rpx;color: #d0d0d0;">加载失败text>view>
<view class="item-menu-name">{{item1.name}}view>
view>
view>
view>
view>
scroll-view>
view>
view>
template>
JavaScript业务逻辑代码：
data() {
return {
scrollTop: 0, //tab标题的滚动条位置
oldScrollTop: 0, // tab标题的滚动条旧位置
current: 0, // 预设当前项的值
menuHeight: 0, // 左边菜单的高度
menuItemHeight: 0, // 左边菜单item的高度
itemId: '', // 栏目右边scroll-view用于滚动的id
tabbar: JSON.parse(uni.getStorageSync('categroy')), // 渲染的数据，放在最后供你们测试
arr: [], // 储存距离顶部高度的数组
scrollRightTop: 0, // 右边栏目scroll-view的滚动条高度
timer: null // 定时器
}
}
CSS代码：
.u-wrap {
/* #ifdef H5 */
height: calc(100vh - var(--window-top));
/* #endif */
display: flex;
flex-direction: column;
height: 100vh;
}
.u-search-box {
padding: 18rpx 30rpx;
}
.u-menu-wrap {
flex: 1;
display: flex;
overflow: hidden;
}
.u-tab-view {
width: 200rpx;
height: 100%;
}
.u-tab-item {
height: 110rpx;
background: #f6f6f6;
box-sizing: border-box;
display: flex;
align-items: center;
justify-content: center;
font-size: 26rpx;
color: #444;
font-weight: 400;
line-height: 1;
}
.u-tab-item-active {
position: relative;
color: #06A446;
font-size: 30rpx;
font-weight: 500;
background: #D6FFE7;
}
.u-tab-item-active::before {
content: "";
position: absolute;
border-left: 4px solid #06A446;
height: 52rpx;
left: 0;
top: 29rpx;
}
.u-tab-view {
height: 100%;
}
.right-box {
background-color: rgb(250, 250, 250);
}
.page-view {
padding: 16rpx;
}
.class-item {
margin-bottom: 30rpx;
background-color: #fff;
padding: 16rpx;
border-radius: 8rpx;
}
.class-item:last-child {
min-height: 100vh;
}
.item-title {
font-size: 26rpx;
color: $u-main-color;
font-weight: bold;
}
.item-menu-name {
margin-top: 8rpx;
font-weight: normal;
font-size: 24rpx;
color: $u-main-color;
}
.item-container {
display: flex;
flex-wrap: wrap;
}
.thumb-box {
width: 33.333333%;
display: flex;
align-items: center;
justify-content: center;
flex-direction: column;
margin-top: 20rpx;
}
.item-menu-image {
width: 120rpx;
height: 120rpx;
}
二、添加逻辑层业务
- 分别获取左侧和右侧每一个类别的高度
我们知道，在
uniapp里面没有window对象和dom元素，所以如果我们要获取页面上的一些节点信息时，需要通过uni.createSelectorQuery()这个API来获取，这里不再赘述。—— 《传送地址》
/**
* 获取一个目标元素的高度
* @elClass 元素的类名
* @dataVal 储存高度的对象
*/
methods: {
getElRect(elClass, dataVal) {
new Promise((resolve, reject) => {
const query = uni.createSelectorQuery().in(this);
query.select('.' + elClass).fields({
size: true
}, res => {
// 如果节点尚未生成，res值为null，循环调用执行
if (!res) {
setTimeout(() => {
this.getElRect(elClass);
}, 10);
return;
}
this[dataVal] = res.height;
resolve();
}).exec();
})
}
}
- 计算右侧每个分类距离顶部的高度并保存
onReady() {
this.getMenuItemTop()
},
mehods: {
/**
* 获取右边菜单每个item到顶部的距离
* 储存到 arr 数组里面用于后面滚动判断
*/
getMenuItemTop() {
new Promise(resolve => {
let selectorQuery = uni.createSelectorQuery();
selectorQuery.selectAll('.class-item').boundingClientRect((rects) => {
// 如果节点尚未生成，rects值为[](因为用selectAll，所以返回的是数组)，循环调用执行
if(!rects.length) {
setTimeout(() => {
this.getMenuItemTop();
}, 10);
return ;
}
rects.forEach((rect) => {
// 视情况而定，这里减去rects[0].top，是因为第一项顶部可能不是贴到导航栏(比如有个搜索框的情况)
// this.arr.push(rect.top - rects[0].top);
this.arr.push(rect.top)
resolve();
})
}).exec()
})
},
}
- 监听右侧元素滚动时交互的状态
节点布局交叉状态 API 可用于监听两个或多个组件节点在布局位置上的相交状态。这一组API常常可以用于推断某些节点是否可以被用户看见、有多大比例可以被用户看见。这里也不再赘述，不懂的直接阅读文档 —— 《传送地址》
methods: {
/**
* 观测元素相交状态
* 检测右边scroll-view的id为itemxx的元素与right-box的相交状态
* 如果跟.right-box底部相交，就动态设置左边栏目的活动状态
*/
async observer() {
this.tabbar.map((val, index) => {
let observer = uni.createIntersectionObserver(this);
observer.relativeTo('.right-box', {
top: 0
}).observe('#item' + index, res => {
if (res.intersectionRatio > 0) {
let id = res.id.substring(4);
this.leftMenuStatus(id);
}
})
})
},
/**
* 设置左边菜单的滚动状态
* @index 传入的 ID
*/
async leftMenuStatus(index) {
this.current = index;
// 如果为0，意味着尚未初始化
if (this.menuHeight == 0 || this.menuItemHeight == 0) {
await this.getElRect('menu-scroll-view', 'menuHeight');
await this.getElRect('u-tab-item', 'menuItemHeight');
}
// 将菜单活动item垂直居中
this.scrollTop = index * this.menuItemHeight + this.menuItemHeight / 2 - this.menuHeight / 2;
}
}
- 实现左侧菜单点击联动右侧滚动
methods: {
/**
* 点击左边的栏目切换
* @index 传入的 ID
*/
async swichMenu(index) {
if(this.arr.length == 0) {
await this.getMenuItemTop();
}
if (index == this.current) return;
this.scrollRightTop = this.oldScrollTop;
this.$nextTick(function(){
this.scrollRightTop = this.arr[index];
this.current = index;
this.leftMenuStatus(index);
})
},
}
- 实现右侧菜单滚动联动左侧高亮
methods: {
/**
* 右边菜单滚动
* 如果不存在height2，意味着数据循环已经到了最后一个，设置左边菜单为最后一项即可
*/
async rightScroll(e) {
this.oldScrollTop = e.detail.scrollTop;
if(this.arr.length == 0) {
await this.getMenuItemTop();
}
if(this.timer) return ;
if(!this.menuHeight) {
await this.getElRect('menu-scroll-view', 'menuHeight');
}
setTimeout(() => { // 节流
this.timer = null;
// scrollHeight为右边菜单垂直中点位置
// let scrollHeight = e.detail.scrollTop + this.menuHeight / 2;
// scrollHeight为右边菜单头部位置
let scrollHeight = e.detail.scrollTop + 20;
for (let i = 0; i < this.arr.length; i++) {
let height1 = this.arr[i];
let height2 = this.arr[i + 1];
if (!height2 || scrollHeight >= height1 && scrollHeight < height2) {
this.leftMenuStatus(i);
return ;
}
}
}, 10)
}
}
三、最后tabbar数据
[
{
"name":"蔬菜水果",
"foods":[
{
"cat":383,
"name":"蔬菜",
"icon":"http://nq348.com/uploads/category/20220315/1aeed6fa43b54cd68cce0c4883160f91.png",
"key":"蔬菜"
},
{
"cat":384,
"name":"食用菌",
"icon":"http://nq348.com/uploads/category/20220418/09839c618b35b510d50151f9a17793ee.png",
"key":"食用菌"
},
{
"cat":385,
"name":"水果",
"icon":"http://nq348.com/uploads/category/20220418/5294ad2fc7effc9629cbfdb8baf41773.png",
"key":"水果"
}
]
},
{
"name":"畜禽养殖",
"foods":[
{
"cat":388,
"name":"禽类",
"icon":"http://nq348.com/uploads/category/20220418/da31895fc5a9aacf93fea6f27f08afd7.png",
"key":"禽类"
},
{
"cat":389,
"name":"畜类",
"icon":"http://nq348.com/uploads/category/20220418/6352081e3f3b36f9360a933676e9452c.png",
"key":"畜类"
},
{
"cat":391,
"name":"蛋类",
"icon":"http://nq348.com/uploads/category/20220418/d2e7ab4224679c0c796ba3ddd8a68e2f.png",
"key":"蛋类"
},
{
"cat":390,
"name":"水产",
"icon":"http://nq348.com/uploads/category/20220418/52a1f1baa7617ef4d4e1a4b344b2fce7.png",
"key":"水产"
}
]
},
{
"name":"粮油副食",
"foods":[
{
"cat":393,
"name":"米面粮油",
"icon":"http://nq348.com/uploads/category/20220418/1bb32e319ecf5aa352b7fe26fc265004.png",
"key":"米面粮油"
},
{
"cat":394,
"name":"坚果干果",
"icon":"http://nq348.com/uploads/category/20220418/6ded13eae4a3b113b5225ca8b99bbfdd.png",
"key":"坚果干果"
},
{
"cat":395,
"name":"加工食品",
"icon":"http://nq348.com/uploads/category/20220418/1e1c10838799de5834aa77f0f9eb8f40.png",
"key":"加工食品"
},
{
"cat":396,
"name":"茶烟酒",
"icon":"http://nq348.com/uploads/category/20220418/c43cd994e49023c7efdf2b18b1bca30b.png",
"key":"茶烟酒"
}
]
},
{
"name":"花卉苗木",
"foods":[
{
"cat":398,
"name":"鲜花盆景",
"icon":"http://nq348.com/uploads/category/20220418/b21c44045daaa8b8d148981ba9efc2e0.png",
"key":"鲜花盆景"
},
{
"cat":399,
"name":"果树苗",
"icon":"http://nq348.com/uploads/category/20220418/63ee2b902ff0f4d638d8a5ad770f7641.png",
"key":"果树苗"
},
{
"cat":400,
"name":"蔬瓜种子",
"icon":"http://nq348.com/uploads/category/20220418/2df521877616ee44fd01aae0434a5815.png",
"key":"蔬瓜种子"
},
{
"cat":401,
"name":"经济作物",
"icon":"http://nq348.com/uploads/category/20220418/f85be72a98694befd889f30de45a1d64.png",
"key":"经济作物"
}
]
},
{
"name":"中草药材",
"foods":[
{
"cat":403,
"name":"全草类",
"icon":"http://nq348.com/uploads/category/20220418/01812c1a83f5db7eafbf3bdae927f134.png",
"key":"全草类"
},
{
"cat":405,
"name":"根茎皮叶花",
"icon":"http://nq348.com/uploads/category/20220418/dca8dcc814401474d4f19ae7394cc209.png",
"key":"根茎皮叶花"
},
{
"cat":406,
"name":"滋补品类",
"icon":"http://nq348.com/uploads/category/20220418/33b965295811fdd6f5e672e9a3ce34a2.png",
"key":"滋补品类"
},
{
"cat":404,
"name":"果实籽仁类",
"icon":"http://nq348.com/uploads/category/20220418/1dc8c46c66b4625d458a7f45787ecef9.png",
"key":"果实籽仁类"
}
]
},
{
"name":"其他",
"foods":[
{
"cat":434,
"name":"包装",
"icon":"http://nq348.com/uploads/category/20220418/ebdfd326333344825adbe81dbd89e2c9.png",
"key":"包装"
},
{
"cat":435,
"name":"安全溯源",
"icon":"http://nq348.com/uploads/category/20220418/03230c63f066f46005abf5f576df0ed1.png",
"key":"安全溯源"
},
{
"cat":436,
"name":"农用百货",
"icon":"http://nq348.com/uploads/category/20220418/93393f2df3264faba86bb449a0c10a79.png",
"key":"农用百货"
},
{
"cat":437,
"name":"仓储物流",
"icon":"http://nq348.com/uploads/category/20220418/f553505ebabbcb1bf762b288716cf1e7.png",
"key":"仓储物流"
}
]
}
]