vue左右侧联动滚动的实现代码

本文介绍了vue左右侧联动滚动的实现代码，分享给大家，具体如下：

实现功能:

1. 点击左侧,右侧滚动到相应位置,
2. 滚动右侧, 左侧滚动到相应位置

布局结构:

开源滚动库:

better-scroll.js

技术要点:

1.<scroll>是对紧邻的元素生效

如:

<scroll class='foods-wrapper'>
 <ul class=content>
 <li></li>
 </ul>
 </scroll>

初始化在<ul>元素上

2.foods-wrapper的高度小于content高度时才会发生滚动

3.点击左侧菜单列表时,只需要计算右侧对应的偏移距离 或是 计算对应的移动到的元素即可

方法一: 计算移动距离, 用scrollTo()方法

 for (let i = 0; i < index; i++) {
 height += this.$refs.item[i].offsetHeight
 }
 this.$refs.foodsWrapper.scrollTo(0, -height)

方法二: 计算移动到的元素,用scrollToElement()方法

 let foodsEle = this.$refs.foodsUl.getElementsByClassName('item')[index]
 this.$refs.foodsWrapper.scrollToElement(foodsEle, 400)

4.滚动右侧列表时,会稍复杂一些.

4.1. 因为需要知道滚动的元素在哪个item列表区间, 因此需要计算右侧五组item距离顶部的距离

_heightArr () {
 let h = 0
 let list = this.$refs.item
 list.forEach((item, i) => {
 h += list[i].clientHeight
 this.itemHeight.push(h)
 })
 console.log(this.itemHeight) //[0, 481, 850, 2227, 2820, 3189]
}

4.2 时时监听滚动距离

需要在<scroll>中加以下参数

代码如下:<scroll class='foods-wrapper' :listenScroll=listenScroll :probeType = 'probeType' @scroll=scroll>

其中 listenScroll probeType参数 在created中定义:

 created () {
 this.listenScroll = true
 this.probeType = 3
 }

而@scroll=scroll是在scroll.vue中代理过来的方法:

 //scroll.vue
 if (this.listenScroll) {
 let me = this
 this.scroll.on('scroll', (position) => {
 me.$emit('scroll', position) //参数position: position:{x:-10, y:24}
 })
 }

posiiton.y就是需要实时监听的参数,即:

scroll (position) {
 this.scrolly = position.y
}

其中 scrolly 需要在data中提前定义:

 data () {
 return {
 scrolly: -1
 }
 }

然后在watch中监听scrolly变化即可:

 watch: {
 scrolly (newy) {
 if (newy >= 0) this.currentIndex = 0
 let itemHeight = this.itemHeight
 for (let i = 0; i < itemHeight.length - 1; i++) {
 let h1 = itemHeight[i]
 let h2 = itemHeight[i + 1]
 if (-newy >= h1 && -newy < h2) {
 this.currentIndex = i
 return
 }
 }
 }
 }

代码部分:

//左侧结构
 <scroll class='menu-wrapper'>
 <ul>
 <li 
 v-for='(item,index) in foodsList' 
 :key=index 
 class=item 
 :class="{active:currentIndex === index}" 
 @click=selectMenu(index)
 >
 <span>{{item.name}}</span>
 </li>
 </ul>
 </scroll>


//右侧结构
 <scroll class='foods-wrapper' ref=foodsWrapper :listenScroll=listenScroll :probeType = 'probeType' @scroll=scroll>
 <ul ref=foodsUl> 
 <li v-for='(item,index) in foodsList' :key=index class=item ref=item :data-index=index>
 <div class=title><span class='title-name'>{{item.name}}</span><span>{{item.description}}</span></div>
 <ul>
 <li v-for='(food,i) in item.foods' :key=i class=food>
 //.........
 //略去右侧详情代码
 </li>
 </ul>
 </li>
 </ul>
 </scroll>

//js部分
<script>
import Scroll from "base/scroll"
const H = 112
export default {
 data () {
 return {
 currentIndex: 0,
 offset: 0,
 scrolly: -1
 }
 },
 created () {
 this.listenScroll = true
 this.probeType = 3
 this.itemHeight = [0]
 },
 mounted () {
 this.$nextTick(() => {
 this._heightArr()
 }, 20);
 },
 methods: {
 selectMenu (index) {
 let height = 0
 this.currentIndex = index

 for (let i = 0; i < index; i++) {
 height += this.$refs.item[i].offsetHeight
 }

 let foodsEle = this.$refs.foodsUl.getElementsByClassName('item')[index]
 this.$refs.foodsWrapper.scrollToElement(foodsEle, 400)
 // this.$refs.foodsWrapper.scrollTo(0, -height)
 this.offset = height
 },
 scroll (position) {
 this.scrolly = position.y
 },
 _heightArr () {
 let h = 0
 let list = this.$refs.item
 list.forEach((item, i) => {
 h += list[i].clientHeight
 this.itemHeight.push(h)
 })
 }
 },
 watch: {
 scrolly (newy) {
 if (newy >= 0) this.currentIndex = 0
 let itemHeight = this.itemHeight
 for (let i = 0; i < itemHeight.length - 1; i++) {
 let h1 = itemHeight[i]
 let h2 = itemHeight[i + 1]
 if (-newy >= h1 && -newy < h2) {
 this.currentIndex = i
 return
 }
 }
 }

 },
 components: {
 Scroll
 }


}
</script>

//scroll.vue
<template>
 <div ref=wrapper>
 <slot></slot> 
 </div>
</template>

<script>
import BScroll from 'better-scroll'
export default {
 props: {
 probeType: {
 type: Number,
 default: 1//* 1 滚动的时候会派发scroll事件，会截流。 * 2 滚动的时候实时派发scroll事件，不会截流。 * 3 除了实时派发scroll事件，在swipe的情况下仍然能实时派发scroll事件
 },
 click: {
 type: Boolean,
 default: true
 },
 scrollX: {
 type: Boolean,
 default: false
 },
 data: {
 type: Array,
 default: null
 },
 listenScroll: {
 type: Boolean,
 default: false
 },

 },
 mounted () {
 this.$nextTick(() => {
 this.initScroll()
 }, 20)
 },
 methods: {
 initScroll () {
 if (!this.$refs.wrapper) return
 this.scroll = new BScroll(this.$refs.wrapper, {
 probeType: this.probeType,
 click: this.click,
 scrollX: this.scrollX
 })

 if (this.listenScroll) {
 let me = this
 this.scroll.on('scroll', (position) => {
 me.$emit('scroll', position)

 })
 }
 },
 enable () {
 this.scroll && this.scroll.enable()
 },
 disable () {
 this.scroll && this.scroll.disable()
 },
 refresh () {
 this.scroll && this.scroll.refresh()
 },
 scrollTo () {
 this.scroll && this.scroll.scrollTo.apply(this.scroll, arguments)
 },

 scrollToElement () {
 this.scroll && this.scroll.scrollToElement.apply(this.scroll, arguments)
 }

 },
 watch: {
 data () {
 setTimeout(() => {
 this.scroll.refresh()
 }, 20)
 }
 }

}
</script>