十、Vue如何使用better-scroll插件

在我们移动项目开发中，经常会处理滚动列表的功能，有的是横向滚动列表，有的是纵向滚动列表。我们在实现这类滚动效果的时候，一般会使用better-scroll插件。
better-scroll是基于移动端滚动的解决方案，它是基于iscroll重写。better-scroll很强大，不仅可以做普通的滚动列表，还可以做轮播图、Picker等等。
今天我就以“饿了么”来讲解如何使用better-scroll。先看“饿了么”动图：

饿了么

今天我们主要实现以下几个功能：

1、左右侧页面滑动，并且不显示滚动条

2、根据左侧的商品类别对应到右侧相应的选择区间，并且高亮标题

3、根据右侧用户滑动的区间，能够对应到左侧的商品类别，并且高亮选择标题

安装插件

这个很简单，一句话就搞定。

npm install--save better-scroll

以下我们就直接上代码，需要注意的地方我们会说明

样式代码

[v-cloak] {
            display: none;
        }

        .goods {
            position: absolute;
            width: 100%;
            top: 174px;
            bottom: 46px;
            display: flex;
            overflow: hidden;
        }

        .goods .menu-wrapper {
            flex: 0 0 80px;
            width: 80px;
            background: #f3f5f7;
        }

        .goods .menu-wrapper .current {
            position: relative;
            z-index: 10;
            margin-top: -1px;
            background: #FFFFFF;
            font-weight: 700;
            font-size: 14px;
        }

        .goods .menu-wrapper .menu-item {
            display: table;
            height: 54px;
            width: 80px;
            line-height: 14px;
            padding: 0 12px;
            border-bottom: 1px solid rgba(7, 17, 27, .1);
            box-sizing: border-box;
        }

        .goods .menu-wrapper .menu-item .icon {
            display: inline-block;
            width: 12px;
            height: 12px;
            margin-right: 2px;
            -webkit-background-size: 12px 12px;
            background-size: 12px 12px;
            background-repeat: no-repeat;
            vertical-align: top;
        }

        .goods .menu-wrapper .menu-item .text {
            display: table-cell;
            width: 56px;
            vertical-align: middle;
            font-size: 12px;
            text-align: center;
        }

        .goods .menu-wrapper .menu-item .decrease {
            background-image: url(img/decrease_2@2x.png);
        }

        .goods .menu-wrapper .menu-item .discount {
            background-image: url(img/decrease_2@2x.png);
        }

        .goods .menu-wrapper .menu-item .guarantee {
            background-image: url(img/decrease_2@2x.png);
        }

        .goods .menu-wrapper .menu-item .invoice {
            background-image: url(img/decrease_2@2x.png);
        }

        .goods .menu-wrapper .menu-item .special {
            background-image: url(img/decrease_2@2x.png);
        }

        .goods .foods-wrapper {
            flex: 1;
        }

        .goods .foods-wrapper .title {
            padding-left: 14px;
            height: 26px;
            line-height: 26px;
            border-left: 2px solid #d9dde1;
            font-size: 12px;
            color: rgb(147, 153, 159);
            background: #F3F5F7;
        }

        .goods .foods-wrapper .current {
            color: #42B983;
            font-size: 14px;
            transition: all .5s;
            line-height: 27px;
        }

        .goods .foods-wrapper .food-item {
            display: flex;
            margin: 18px 0 18px 0;
            border-bottom: 1px solid rgba(7, 17, 27, .1);
            padding-bottom: 18px;
        }

        .goods .foods-wrapper .food-item:last-child {
            border-bottom: 0px solid rgba(7, 17, 27, .1);
            margin-bottom: 0;
        }

        .goods .foods-wrapper .food-item .icon {
            flex: 0 0 57px;
            margin-right: 10px;
            margin-left: 10px;
        }

        .goods .foods-wrapper .food-item .content {
            position: relative;
            flex: 1;
        }

        .goods .foods-wrapper .food-item .content .name {
            margin: 2px 0 8px 0;
            height: 14px;
            line-height: 14px;
            font-size: 14px;
            color: rgb(7, 17, 27);
        }

        .goods .foods-wrapper .food-item .content .desc {
            margin-bottom: 8px;
            line-height: 10px;
            font-size: 10px;
            color: rgb(147, 153, 159);
        }

        .goods .foods-wrapper .food-item .content .extra {
            font-size: 10px;
            color: rgb(147, 153, 159);
            line-height: 10px;
        }

        .goods .foods-wrapper .food-item .content .extra .count {
            margin-right: 12px;
        }

        .goods .foods-wrapper .food-item .content .price {
            font-weight: 700;
            line-height: 24px;
        }

        .goods .foods-wrapper .food-item .content .price .now {
            margin-right: 8px;
            font-size: 14px;
            color: rgb(240, 20, 20);
        }

        .goods .foods-wrapper .food-item .content .price .old {
            text-decoration: line-through;
            font-size: 10px;
            color: rgb(147, 153, 159);
        }

        .goods .foods-wrapper .food-item .content .cartcontrol-wrapper {
            position: absolute;
            right: 6px;
            bottom: 12px;
        }

页面布局

<template>
<div class="goods" v-cloak>
            <div class="menu-wrapper" ref="menuwrapper">
                <ul>
                    <!--当currentIndex与index相等的时候，设置高亮-->
                    <li v-for="(item,index) in goods" class="menu-item" :class="{'current':currentIndex === index}" @click="selectMenu(index,$event)" v-cloak>
                        <span class="text">
                                <span v-show="item.type>0" class="icon" :class="classMap[item.type]" v-cloak></span> {{item.name}}
                        </span>
                    </li>
                </ul>
            </div>
            <div class="foods-wrapper" ref="foodwrapper">
                <ul>
                    <!--food-list-hook用于dom操作，获取整体容器的高度-->
                    <li v-for="(item,index) in goods" class="food-list food-list-hook" v-cloak>
                        <h2 class="title" :class="{'current':currentIndex === index}">{{item.name}}</h2>
                        <ul>
                            <li @click="selectfood(food,$event)" v-for="food in item.foods" class="food-item">
                                <div class="icon">
                                    ![](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>
                                    <div class="price">
                                        <span class="now">￥{{food.price}}</span>
                                        <span v-show="food.oldPrice" class="old">￥{{food.oldPrice}}</span>
                                    </div>
                                </div>
                            </li>
                        </ul>
                    </li>
                </ul>
            </div>
        </div>  
</template>

JS代码

<script>
export default {
 data() {
      return {
       msg: 'goods',
                goods: [],
                listHeight: [],
                scrollY: 0,
      }
    },
created() {
                this.classMap = ['decrease', 'discount', 'guarantee', 'invoice', 'special'];
                this.$http.get('./data.json').then((res) => {
                    if(res.status === ERR_OK) {
                        res = res.body.goods;
                        this.goods = res;
                        //dom结构加载结束
                        this.$nextTick(() => {
                            this._initScroll();
                            //计算高度
                            this._calculateHeight();
                        })
                    }
                });
            },
computed: {
                currentIndex() {
                    for(let i = 0; i < this.listHeight.length; i++) {
                        //判断当currentIndex在height1和height2之间的时候显示
                        let height1 = this.listHeight[i];
                        let height2 = this.listHeight[i + 1];
                        //          console.log('height1:'+height1+','+'height2:'+height2)
                        //最后一个区间没有height2
                        if(!height2 || (this.scrollY >= height1 && this.scrollY < height2)) {
                            return i;
                        }
                    }
                    return 0;
                }
            },
methods: {
                selectMenu(index, event) {
                    //      自己默认派发事件时候(BScroll),_constructed被置为true,但是浏览器原生并没有这个属性
                    if(!event._constructed) {
                        return;
                    }
                    //运用BScroll接口，滚动到相应位置
                    let foodList = this.$refs.foodwrapper.getElementsByClassName('food-list-hook');
                    //获取对应元素的列表
                    let el = foodList[index];
                    this.foodScroll.scrollToElement(el, 300);
                },
                 /*
                  _initScroll的函数，主要用来对左右两侧dom结构进行初始化 
                 用better-scroll的方法初始化需要滚动的dom结构，
                vue为我们提供了一个方法可以便利的获取到 dom结构，
                我们在需要获取dom结构的父容器内添加ref="foodwrapper" ，
               然后在函数内用this.$refs.menuwrapper获取到dom
                */
                _initScroll() {
                    this.meunScroll = new BScroll(this.$refs.menuwrapper, {
                        click: true
                    });
                    this.foodScroll = new BScroll(this.$refs.foodwrapper, {
                        click: true,
                        //探针作用，实时监测滚动位置
                        probeType: 3
                    });
                    //设置监听滚动位置
                    this.foodScroll.on('scroll', (pos) => {
                        //scrollY接收变量
                        this.scrollY = Math.abs(Math.round(pos.y));
                    })
                },
                _calculateHeight() {
                    let foodList = this.$refs.foodwrapper.getElementsByClassName('food-list-hook');
                    let height = 0;
                    //把第一个高度送入数组
                    this.listHeight.push(height);
                    //通过循环foodList下的dom结构，将每一个li的高度依次送入数组
                    for(let i = 0; i < foodList.length; i++) {
                        let item = foodList[i]
                        height += item.clientHeight
                        this.listHeight.push(height);
                    }
                },
            }
}
</script>

最后完整的效果图如下：

最终效果图
感兴趣的朋友可以去试试。
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