vue和better-scroll实现列表左右联动效果详解

一.实现思路

1. (1)实现上是左右分别一个better-scroll列表
2. (2)利用计算右侧列表每一个大区块的高度来计算左侧的位置

二.实现

1.实现左右两个better-scroll

(1)dom结构(better-scroll要求,会把最外层dom的第一个子元素作为要滚动的区域)

左边滚动列表dom
 <div class="menu-wrapper" v-el:menu-wrapper>
   <ul>
    <li v-for="item in goods" class="menu-item"
      :class="{'current':currentIndex === $index}"
      @click="selectMenu($index,$event)">
     <span class="text border-1px">
      <span v-show="item.type > 0" class="icon"
       :class="classMap[item.type]"></span>{{item.name}}
     </span>
    </li>
   </ul>
  </div>

右边滚动列表dom
<div class="food-wrapper" v-el:food-wrapper>
   <ul>
    <li v-for="item in goods" class="food-list food-list-hook">
     <h1 class="title">{{item.name}}</h1>
     <ul>
      <li v-for="food in item.foods" class="food-item border-1px">
       <div class="icon">
        <img width="57" height="57" :src="food.icon">
       </div>
       <div class="content">
        <h2 class="name">{{food.name}}</h2>
        <p class="desc">{{food.description}}</p>
        <div class="extra">
         <span class="count">月售{{food.sellCount}}份</span>
         <span>好评率{{food.rating}}%</span>
         <div class="price">
          <span class="now">¥{{food.price}}</span>
          <span class="old" v-show="food.oldPrice">¥{{food.oldPrice}}</span>
         </div>
        </div>
       </div>
      </li>
     </ul>
    </li>
   </ul>
  </div>

在数据请求完成后的$nextTick中初始化better-scroll,就能实现两个列表分别能滚动,至于联动,要后面自己做

_initScroll() {
    this.menuScroll = new BScroll(this.$els.menuWrapper,{
     click:true  //允许better-scroll列表上的点击事件
    });
    this.foodsScroll = new BScroll(this.$els.foodWrapper,{
     probeType : 3  //让better-scroll监听scroll事件
    });
    this.foodsScroll.on('scroll',(pos) => {
     this.scrollY =Math.abs(Math.round(pos.y));
    })
   },

2.实现联动效果

(1)具体的联动实现思路

1. 在渲染完成后($nextTick内),初始化better-scroll,并在初始化函数内添加右侧列表的scroll监听事件,并记录scrollY值到,存入vue的data中
2. 在渲染完成后($nextTick内),计算右侧列表的每一个大区块的高度,并累加,存入数组listHeight
3. 因为scrollY值在滚动中总是不断变化的,所以在computed中计算出currentIndex,当前滚动区域是哪一个大区块,也就是listHeight数组的下标
4. 在dom中根据currentIndex应用左侧列表被点中的样式
5. 在左侧列表某一项被点中的时候,右侧列表滑动到某一个大块区域,
   

//初始化better-scroll
_initScroll() {
    this.menuScroll = new BScroll(this.$els.menuWrapper,{
     click:true
    });
    this.foodsScroll = new BScroll(this.$els.foodWrapper,{
     probeType : 3
    });
    this.foodsScroll.on('scroll',(pos) => {
     this.scrollY =Math.abs(Math.round(pos.y));
    })
   },

_calculateHeight() {
    let foodList = this.$els.foodWrapper.getElementsByClassName("food-list-hook");
    let height = 0;
    this.listHeight.push(height);
    for(let i=0;i<foodList.length;i++) {
     let item = foodList[i];
     height += item.clientHeight;
     this.listHeight.push(height);
    }
   }

computed: {
   currentIndex() {
    for(let i=0;i< this.listHeight.length;i++) {
     let height1 = this.listHeight[i];
     let height2 = this.listHeight[i+1];
     if(!height2 || (this.scrollY >= height1 && this.scrollY < height2)){
      return i;
     }
    }
    return 0;
   }
  },

<div class="menu-wrapper" v-el:menu-wrapper>
   <ul>
    <!-- :class="{'current':currentIndex === $index}" 就是根据currentIndex应用左侧列表被点中的样式 -->
    <li v-for="item in goods" class="menu-item"
      :class="{'current':currentIndex === $index}"
      @click="selectMenu($index,$event)">
     <span class="text border-1px">
      <span v-show="item.type > 0" class="icon"
       :class="classMap[item.type]"></span>{{item.name}}
     </span>
    </li>
   </ul>
  </div>

//被点击事件
//dom
<div class="menu-wrapper" v-el:menu-wrapper>
   <ul>
    <!-- @click="selectMenu($index,$event)" 就是点击事件 -->
    <li v-for="item in goods" class="menu-item"
      :class="{'current':currentIndex === $index}"
      @click="selectMenu($index,$event)">
     <span class="text border-1px">
      <span v-show="item.type > 0" class="icon"
       :class="classMap[item.type]"></span>{{item.name}}
     </span>
    </li>
   </ul>
  </div>
//js  
selectMenu(index,event) {
    if(!event._constructed) {
     return ;
    }
    let foodList = this.$els.foodWrapper.getElementsByClassName("food-list-hook");
    let el = foodList[index];
    this.foodsScroll.scrollToElement(el,300);
   },

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