点击左侧,右侧滚动到相应位置,
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> <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.$refs.item list.forEach((item, i) => { h += list[i].clientHeight this.itemHeight.push(h) }) console.log(this.itemHeight) //[0, 481, 850, 2227, 2820, 3189] }
4.2 时时监听滚动距离
需要在<scroll>中加以下参数
复制代码 代码如下:
<scroll :listenScroll=listenScroll :probeType = 'probeType' @scroll=scroll>
其中 listenScroll probeType参数 在created中定义:
created () { this.listenScroll = true this.probeType = 3 }
而@scroll=scroll是在scroll.vue中代理过来的方法:
//scroll.vue if (this.listenScroll) { let me = this this.scroll.on('scroll', (position) => { me.$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> <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 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>{{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>