Vue实战项目开发--城市列表页面

本是古典何须时尚 2022-05-15 16:18 397阅读 0赞

### 城市选择页面路由配置 ###

*  创建一个city-router的分支，用于城市列表的功能实现
 *  路由配置，修改router/index.js的内容
    
        import Vue from 'vue'
        import Router from 'vue-router'
        
        Vue.use(Router)
        
        export default new Router({
          routes: [
            {
              path: '/',
              name: 'Home',
              component:  () => import( '@/pages/home/Home')
            },
            {
              path: '/city',
              name: 'City',
              component:  () => import( '@/pages/city/City')
            }
          ]
        })
    
    然后在pages文件夹下新建city文件夹，并创建City.vue，最后在city文件夹下新建components文件夹，然后创建City.vue的顶部Header.vue             
 *  City.vue：
    
        <template>
          <div>
            <city-header></city-header>
          </div>
        </template>
        <script>
        import CityHeader from './components/Header'
        export default {
          name:'City',
          components: {
            CityHeader
          },
          data () {
            return {
              
            }
          }
        }
        </script>
        <style lang="stylus" scoped>
        
        </style>
    
    Header.vue:
    
        <template>
          <div class="header">
            城市选择
            <router-link to='/'>
               <div class="iconfont header-back"></div>
            </router-link>
          </div>
        </template>
        <script>
        export default {
          name:'CityHeader',
          data () {
            return {
              
            }
          }
        }
        </script>
        <style lang="stylus" scoped>
          @import '~styles/varibles.styl'
          .header
            position relative
            height $headerHeight
            line-height $headerHeight
            text-align center
            color #fff
            background $bgColor
            font-size .32rem
            .header-back
              position absolute
              top 0
              left 0
              width .64rem
              text-align center
              font-size .4rem
              color #ffffff
        </style>
    
     
 *  实现点击首页的header部分的成都进入城市列表和点击城市列表的返回按钮返回首页，这里使用router-link实现的，router-link类似a标签
    
        <router-link to='/city'>
               <div class="header-right">
                {
             {this.city}}
                <i class="iconfont arrow-icon"></i>
              </div>
        </router-link>
    
        <router-link to='/'>
               <div class="iconfont header-back"></div>
         </router-link>

*  代码优化：这里把顶部的height在varibles.styl文件中定义为一个常量，方便后期修改
    
        $headerHeight = .86rem
    
    使用
    
        @import '~styles/varibles.styl'   （这里需要先引入才可以使用）
         
        height $headerHeight  
        line-height $headerHeight
    
    最后，把代码提交到GitHub上

### 搜索框布局 ###

*  创建city-search分支，然后把本地的项目改在新建的这个分支上进行开发
 *  在components中新建Search.vue文件
    
        <template>
          <div class="search">
            <input class="search-input" type="text" placeholder="输入城市名或拼音">
          </div>
        </template>
        <script>
        export default {
          name:'CitySearch',
          data () {
            return {
              
            }
          }
        }
        </script>
        <style lang="stylus" scoped>
          @import '~styles/varibles.styl'
          .search
            height .72rem
            padding 0 .1rem
            background $bgColor
            .search-input
              box-sizing border-box
              width 100%
              height .62rem
              padding 0 .1rem
              line-height .62rem
              text-align center
              border-radius .06rem
              color #666666
        </style>
    
    然后在City.vue中引入并使用
    
        <template>
          <div>
            <city-header></city-header>
            <city-search></city-search>
          </div>
        </template>
        <script>
        import CityHeader from './components/Header'
        import CitySearch from './components/Search'
        
        export default {
          name:'City',
          components: {
            CityHeader,
            CitySearch
          },
          data () {
            return {
              
            }
          }
        }
        </script>
        <style lang="stylus" scoped>
        
        </style>
    
    然后搜索框布局就完成了，最后把代码提交到GitHub上

### 列表布局 ###

*  创建city-list分支，然后把本地的项目改在新建的这个分支上进行开发
 *  在components中新建List.vue文件
    
        <template>
          <div class="list">
            <div class="area">
              <div class="title border-topbottom">当前城市</div>
              <div class="button-list">
                <div class="button-wrapper">
                  <div class="button">成都</div>
                </div>
              </div>
            </div>
            <div class="area">
              <div class="title border-topbottom">热门城市</div>
              <div class="button-list">
                <div class="button-wrapper">
                  <div class="button">成都</div>
                </div>
                <div class="button-wrapper">
                  <div class="button">成都</div>
                </div>
                <div class="button-wrapper">
                  <div class="button">成都</div>
                </div>
                <div class="button-wrapper">
                  <div class="button">成都</div>
                </div>
              </div>
            </div>
            <div class="area">
              <div class="title border-topbottom">A</div>
              <div class="item-list">
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
              </div>
            </div>
            <div class="area">
              <div class="title border-topbottom">B</div>
              <div class="item-list">
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
              </div>
            </div>
            <div class="area">
              <div class="title border-topbottom">C</div>
              <div class="item-list">
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
              </div>
            </div>
            <div class="area">
              <div class="title border-topbottom">D</div>
              <div class="item-list">
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
                <div class="item border-bottom">阿拉尔</div>
              </div>
            </div>
        
          </div>
        </template>
        <script>
        export default {
          name:'CityList',
        }
        </script>
        <style lang="stylus" scoped>
          @import '~styles/varibles.styl'
          .border-topbottom
            &:before
              border-color #ccc
            &:after
              border-color #ccc
           .border-bottom
            &:before
              border-color #ccc
          .list
            overflow hidden
            position absolute
            top 1.58rem
            left 0
            right 0
            bottom 0
            .title
              line-height .44rem
              background #eee
              padding-left .2rem
              color #666
              font-size .26rem
            .button-list
              padding .1rem .6rem .1rem .1rem
              overflow hidden 
              .button-wrapper
                float left
                width 33.33%
                .button
                  margin .1rem
                  padding .1rem 0
                  text-align center
                  border .02rem solid #ccc
                  border-radius .06rem
            .item-list
            .item
              line-height .76rem
              padding-left .2rem
        </style>
    
    然后在City.vue中引入并使用
    
        <template>
          <div>
            <city-header></city-header>
            <city-search></city-search>
            <city-list></city-list>
          </div>
        </template>
        <script>
        import CityHeader from './components/Header'
        import CitySearch from './components/Search'
        import CityList from './components/List'
        
        export default {
          name:'City',
          components: {
            CityHeader,
            CitySearch,
            CityList
          }
        }
        </script>
        <style lang="stylus" scoped>
        
        </style>
    
    然后列表布局就完成了，最后把代码提交到GitHub上

### Better-scroll的使用及字母表布局 ###

*  安装better-scroll插件
    
        npm install better-scroll --save
    
    在文档可以看到better-scroll的使用[better-scroll的GitHub地址][better-scroll_GitHub]
 *   修改List.vue的代码
    
        <div class="list" ref='wrapper'>    （使用ref来获取当前元素）
            <div>
                 <- 这里放之前的内容 ->
            </div>
          </div>
    
    引入并使用
    
        import BScroll from 'better-scroll'
        export default {
          name:'CityList',
          mounted () {
            this.scroll = new BScroll(this.$refs.wrapper)
          }
        }
    
    完整代码
    
        <template>
          <div class="list" ref='wrapper'>
            <div>
              <div class="area">
                <div class="title border-topbottom">当前城市</div>
                <div class="button-list">
                  <div class="button-wrapper">
                    <div class="button">成都</div>
                  </div>
                </div>
              </div>
              <div class="area">
                <div class="title border-topbottom">热门城市</div>
                <div class="button-list">
                  <div class="button-wrapper">
                    <div class="button">成都</div>
                  </div>
                  <div class="button-wrapper">
                    <div class="button">成都</div>
                  </div>
                  <div class="button-wrapper">
                    <div class="button">成都</div>
                  </div>
                  <div class="button-wrapper">
                    <div class="button">成都</div>
                  </div>
                </div>
              </div>
              <div class="area">
                <div class="title border-topbottom">A</div>
                <div class="item-list">
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                </div>
              </div>
              <div class="area">
                <div class="title border-topbottom">B</div>
                <div class="item-list">
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                </div>
              </div>
              <div class="area">
                <div class="title border-topbottom">C</div>
                <div class="item-list">
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                </div>
              </div>
              <div class="area">
                <div class="title border-topbottom">D</div>
                <div class="item-list">
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                  <div class="item border-bottom">阿拉尔</div>
                </div>
              </div>
             </div>
          </div>
        </template>
        
        <script>
        import BScroll from 'better-scroll'
        export default {
          name:'CityList',
          mounted () {
            this.scroll = new BScroll(this.$refs.wrapper)
          }
        }
        </script>
        <style lang="stylus" scoped>
          @import '~styles/varibles.styl'
          .border-topbottom
            &:before
              border-color #ccc
            &:after
              border-color #ccc
           .border-bottom
            &:before
              border-color #ccc
          .list
            overflow hidden
            position absolute
            top 1.58rem
            left 0
            right 0
            bottom 0
            .title
              line-height .54rem
              background #eee
              padding-left .2rem
              color #666
              font-size .26rem
            .button-list
              padding .1rem .6rem .1rem .1rem
              overflow hidden 
              .button-wrapper
                float left
                width 33.33%
                .button
                  margin .1rem
                  padding .1rem 0
                  text-align center
                  border .02rem solid #ccc
                  border-radius .06rem
            .item-list
            .item
              line-height .76rem
              padding-left .2rem
        </style>
    
    better-scroll就引入并使用完成了
 *  字母表布局：在componens文件夹下新建Alphabet.vue
    
        <template>
          <ul class="list">
            <li class="item">A</li>
            <li class="item">A</li>
            <li class="item">A</li>
            <li class="item">A</li>
            <li class="item">A</li>
          </ul>
        </template>
        <script>
        export default {
          name:'CityAlphabet',
        }
        </script>
        <style lang="stylus" scoped>
          @import '~styles/varibles.styl'
          .list
            display flex
            flex-direction column
            justify-content center
            position absolute
            top 1.58rem
            right 0
            bottom 0
            width .4rem
            .item
              line-height .4rem
              text-align center
              color $bgColor
        </style>
    
    然后在City.vue中引入：
    
        <template>
          <div>
            <city-header></city-header>
            <city-search></city-search>
            <city-list></city-list>
            <city-alphabet></city-alphabet>
          </div>
        </template>
        <script>
        import CityHeader from './components/Header'
        import CitySearch from './components/Search'
        import CityList from './components/List'
        import CityAlphabet from './components/Alphabet'
        
        export default {
          name:'City',
          components: {
            CityHeader,
            CitySearch,
            CityList,
            CityAlphabet
          },
          data () {
            return {
              
            }
          }
        }
        </script>
        <style lang="stylus" scoped>
        
        </style>
    
    字母表布局就完成了，最后把代码提交到线上

### 页面的动态数据渲染 ###

*  创建city-Ajax分支，然后把本地的项目改在新建的这个分支上进行开发
 *  使用Ajax模拟网络请求，在static/mock下新建一个city.json(有需要的可以在我的GitHub上拉取),在使用axios来模拟请求数据
 *  City.vue的js部分：
    
        <script>
        import axios from 'axios'
        import CityHeader from './components/Header'
        import CitySearch from './components/Search'
        import CityList from './components/List'
        import CityAlphabet from './components/Alphabet'
        
        export default {
          name:'City',
          components: {
            CityHeader,
            CitySearch,
            CityList,
            CityAlphabet
          },
          data () {
            return {
              cities: {},
              hotCities: []
            }
          },
          methods: {
            getCityInfo () {
              axios.get('/api/city.json')
                .then(this.handleGetCityInfoSucc)
            },
            handleGetCityInfoSucc (res) {
              console.log(res)
              res = res.data
              if(res.ret && res.data){
                const data = res.data
                this.cities = data.cities
                this.hotCities = data.hotCities
              }
            }
          },
          mounted () {
            this.getCityInfo()
          }
          
        }
        </script>
    
     City.vue：
    
        <template>
          <div>
            <city-header></city-header>
            <city-search></city-search>
            <city-list :cities="cities" :hot="hotCities"></city-list>
            <city-alphabet :cities="cities"></city-alphabet>
          </div>
        </template>
        <script>
        import axios from 'axios'
        import CityHeader from './components/Header'
        import CitySearch from './components/Search'
        import CityList from './components/List'
        import CityAlphabet from './components/Alphabet'
        
        export default {
          name:'City',
          components: {
            CityHeader,
            CitySearch,
            CityList,
            CityAlphabet
          },
          data () {
            return {
              cities: {},
              hotCities: []
            }
          },
          methods: {
            getCityInfo () {
              axios.get('/api/city.json')
                .then(this.handleGetCityInfoSucc)
            },
            handleGetCityInfoSucc (res) {
              console.log(res)
              res = res.data
              if(res.ret && res.data){
                const data = res.data
                this.cities = data.cities
                this.hotCities = data.hotCities
              }
            }
          },
          mounted () {
            this.getCityInfo()
          }
          
        }
        </script>
        <style lang="stylus" scoped>
        
        </style>
    
    List.vue:
    
        <template>
          <div class="list" ref='wrapper'>
            <div>
              <div class="area">
                <div class="title border-topbottom">当前城市</div>
                <div class="button-list">
                  <div class="button-wrapper">
                    <div class="button">成都</div>
                  </div>
                </div>
              </div>
              <div class="area">
                <div class="title border-topbottom">热门城市</div>
                <div class="button-list">
                  <div class="button-wrapper" v-for="item of hot" :key="item.id">
                    <div class="button">{
             {item.name}}</div>
                  </div>
                </div>
              </div>
              <div class="area" v-for="(item,key) of cities" :key="key">
                <div class="title border-topbottom">{
             {key}}</div>
                <div class="item-list">
                  <div class="item border-bottom" v-for="innerItem of item" :key="innerItem.id">{
             {innerItem.name}}</div>
                </div>
              </div>
             </div>
          </div>
        </template>
        
        <script>
        import BScroll from 'better-scroll'
        export default {
          name:'CityList',
          props: {  
            hot: Array,
            cities: Object
          },
          mounted () {
            this.scroll = new BScroll(this.$refs.wrapper)
          }
        }
        </script>
        <style lang="stylus" scoped>
          @import '~styles/varibles.styl'
          .border-topbottom
            &:before
              border-color #ccc
            &:after
              border-color #ccc
           .border-bottom
            &:before
              border-color #ccc
          .list
            overflow hidden
            position absolute
            top 1.58rem
            left 0
            right 0
            bottom 0
            .title
              line-height .54rem
              background #eee
              padding-left .2rem
              color #666
              font-size .26rem
            .button-list
              padding .1rem .6rem .1rem .1rem
              overflow hidden 
              .button-wrapper
                float left
                width 33.33%
                .button
                  margin .1rem
                  padding .1rem 0
                  text-align center
                  border .02rem solid #ccc
                  border-radius .06rem
            .item-list
            .item
              line-height .76rem
              padding-left .2rem
        </style>
    
    Alphabet.vue：
    
        <template>
          <ul class="list">
            <li class="item" v-for="(item,key) of cities" :key="key">{
             {key}}</li>
          </ul>
        </template>
        <script>
        export default {
          name:'CityAlphabet',
          props: {
           cities: Object
          }
        }
        </script>
        <style lang="stylus" scoped>
          @import '~styles/varibles.styl'
          .list
            display flex
            flex-direction column
            justify-content center
            position absolute
            top 1.58rem
            right 0
            bottom 0
            width .4rem
            .item
              line-height .4rem
              text-align center
              color $bgColor
        </style>
    
     
 *  最后看一下最后的效果，记住把代码提交到GitHub上

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvXzkyMTExMA_size_16_color_FFFFFF_t_70][]

### 兄弟组建间联动 ###

*  实现点击右侧字母，左边的内容跟着字母变化

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvXzkyMTExMA_size_16_color_FFFFFF_t_70 1][]

就是点击H字母，城市列表就跳到H首字母的城市列表

这里是通过在Alphabet.vue监听点击字母的点击事件，然后把点击对应的元素的值传给父组件，父组件再将这个值传给List.vue子组件的

Alphabet.vue（增加了handleLetterClick，通过emit把值传给父组件的）：

<template>
      <ul class="list">
        <li 
          class="item" 
          v-for="(item,key) of cities" 
          :key="key"
          @click="handleLetterClick"
        >
          {
       {key}}
        </li>
      </ul>
    </template>
    <script>
    export default {
      name:'CityAlphabet',
      props: {
       cities: Object
      },
      methods: {
        handleLetterClick (e) {
          this.$emit('change',e.target.innerText)
        }
      }
    }
    </script>
    <style lang="stylus" scoped>
      @import '~styles/varibles.styl'
      .list
        display flex
        flex-direction column
        justify-content center
        position absolute
        top 1.58rem
        right 0
        bottom 0
        width .4rem
        .item
          line-height .4rem
          text-align center
          color $bgColor
    </style>

City.vue（通过@change="handleLetterChange"来接受Alphabet.vue子组件传过来的值，并在data中定义letter值，在前面的方法把从子组件得到的值赋给data中定义好的letter，然后把这个值通过属性传给List.vue子组件）：

<template>
      <div>
        <city-header></city-header>
        <city-search></city-search>
        <city-list 
          :cities="cities" 
          :hot="hotCities"
          :letter="letter"
        ></city-list>
        <city-alphabet 
          :cities="cities" 
          @change="handleLetterChange"
        ></city-alphabet>
      </div>
    </template>
    <script>
    import axios from 'axios'
    import CityHeader from './components/Header'
    import CitySearch from './components/Search'
    import CityList from './components/List'
    import CityAlphabet from './components/Alphabet'
    
    export default {
      name:'City',
      components: {
        CityHeader,
        CitySearch,
        CityList,
        CityAlphabet
      },
      data () {
        return {
          cities: {},
          hotCities: [],
          letter: ''
        }
      },
      methods: {
        getCityInfo () {
          axios.get('/api/city.json')
            .then(this.handleGetCityInfoSucc)
        },
        handleGetCityInfoSucc (res) {
          res = res.data
          if(res.ret && res.data){
            const data = res.data
            this.cities = data.cities
            this.hotCities = data.hotCities
          }
        },
        handleLetterChange (letter) {
          this.letter = letter;
        }
      },
      mounted () {
        this.getCityInfo()
      }
      
    }
    </script>
    <style lang="stylus" scoped>
    
    </style>

List.vue（在这里使用props接受父组件传来的letter值，并使用watch来监听letter值的变化，然后让内容跟随右侧字母的变化）:

<template>
      <div class="list" ref='wrapper'>
        <div>
          <div class="area">
            <div class="title border-topbottom">当前城市</div>
            <div class="button-list">
              <div class="button-wrapper">
                <div class="button">成都</div>
              </div>
            </div>
          </div>
          <div class="area">
            <div class="title border-topbottom">热门城市</div>
            <div class="button-list">
              <div class="button-wrapper" v-for="item of hot" :key="item.id">
                <div class="button">{
       {item.name}}</div>
              </div>
            </div>
          </div>
          <div 
            class="area" 
            v-for="(item,key) of cities" 
            :key="key"
            :ref="key"
          >
            <div class="title border-topbottom">{
       {key}}</div>
            <div class="item-list">
              <div class="item border-bottom" v-for="innerItem of item" :key="innerItem.id">{
       {innerItem.name}}</div>
            </div>
          </div>
         </div>
      </div>
    </template>
    
    <script>
    import BScroll from 'better-scroll'
    export default {
      name:'CityList',
      props: {  
        hot: Array,
        cities: Object,
        letter: String
      },
      mounted () {
        this.scroll = new BScroll(this.$refs.wrapper)
      },
      watch: {
        letter () {
          if (this.letter) {
            const element = this.$refs[this.letter][0]
            this.scroll.scrollToElement(element)
          }
        }
      }
    }
    </script>
    <style lang="stylus" scoped>
      @import '~styles/varibles.styl'
      .border-topbottom
        &:before
          border-color #ccc
        &:after
          border-color #ccc
       .border-bottom
        &:before
          border-color #ccc
      .list
        overflow hidden
        position absolute
        top 1.58rem
        left 0
        right 0
        bottom 0
        .title
          line-height .54rem
          background #eee
          padding-left .2rem
          color #666
          font-size .26rem
        .button-list
          padding .1rem .6rem .1rem .1rem
          overflow hidden 
          .button-wrapper
            float left
            width 33.33%
            .button
              margin .1rem
              padding .1rem 0
              text-align center
              border .02rem solid #ccc
              border-radius .06rem
        .item-list
        .item
          line-height .76rem
          padding-left .2rem
    </style>

*   在左侧字母表中做上下拖拽的时候，城市列表内容也跟着变化

主要是监听拖拽时间，在li增加了三个事件，分别是touchstart、touchmove、touchend来监听拖拽事件，同时在li上使用ref，在data定义了一个touchStatus来保存是否在拖拽的状态，并使用计算属性把cities中的字母取出来放在数组letters中，最后计算拖拽到那个字母：

handleTouchStart () {
          this.touchStatus = true
        },
        handleTouchMove (e) {
          if(this.touchStatus){
            const startY = this.$refs['A'][0].offsetTop
            const touchY = e.touches[0].clientY -79
            const index = Math.floor((touchY-startY) / 20)
            if(index >= 0 && index < this.letters.length) {
              this.$emit('change',this.letters[index])
            }
          }
        },
        handleTouchEnd () {
          this.touchStatus = false
        }

Alphabet.vue：

<template>
      <ul class="list">
        <li 
          class="item" 
          v-for="item of letters" 
          :key="item"
          :ref="item"
          @touchstart="handleTouchStart"
          @touchmove="handleTouchMove"
          @touchend="handleTouchEnd"
          @click="handleLetterClick"
        >
          {
       {item}}
        </li>
      </ul>
    </template>
    <script>
    export default {
      name:'CityAlphabet',
      props: {
       cities: Object
      },
      data () {
        return {
          touchStatus: false
        }
      },
      computed: {
        letters () {
          const letters = []
          for( let i in this.cities) {
            letters.push(i)
          }
          return letters
        }
      },
      methods: {
        handleLetterClick (e) {
          this.$emit('change',e.target.innerText)
        },
        handleTouchStart () {
          this.touchStatus = true
        },
        handleTouchMove (e) {
          if(this.touchStatus){
            const startY = this.$refs['A'][0].offsetTop
            const touchY = e.touches[0].clientY -79
            const index = Math.floor((touchY-startY) / 20)
            if(index >= 0 && index < this.letters.length) {
              this.$emit('change',this.letters[index])
            }
          }
        },
        handleTouchEnd () {
          this.touchStatus = false
        }
      }
    }
    </script>
    <style lang="stylus" scoped>
      @import '~styles/varibles.styl'
      .list
        display flex
        flex-direction column
        justify-content center
        position absolute
        top 1.58rem
        right 0
        bottom 0
        width .4rem
        .item
          line-height .4rem
          text-align center
          color $bgColor
    </style>

### 列表切换性能优化 ###

*  把A字母离顶部的高度使用updated钩子函数来计算，不用每次执行handleTouchMove函数的时候都计算

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvXzkyMTExMA_size_16_color_FFFFFF_t_70 2][]

*  函数节流（定义了一个timer，如果正在执行拖拽操作，让它延迟16毫秒来执行，如果在16毫秒之间又执行了手指滑动操作，它就会把上次要做的操作清楚掉，重新执行这次要做的事情，从而减少handleTouchMove函数的执行频率）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvXzkyMTExMA_size_16_color_FFFFFF_t_70 3][]

Alphabet.vue：

<template>
      <ul class="list">
        <li 
          class="item" 
          v-for="item of letters" 
          :key="item"
          :ref="item"
          @touchstart="handleTouchStart"
          @touchmove="handleTouchMove"
          @touchend="handleTouchEnd"
          @click="handleLetterClick"
        >
          {
       {item}}
        </li>
      </ul>
    </template>
    <script>
    export default {
      name:'CityAlphabet',
      props: {
       cities: Object
      },
      data () {
        return {
          touchStatus: false,
          startY: 0,
          timer: ''
        }
      },
      computed: {
        letters () {
          const letters = []
          for( let i in this.cities) {
            letters.push(i)
          }
          return letters
        }
      },
      updated () {
        this.startY = this.$refs['A'][0].offsetTop
      },
      methods: {
        handleLetterClick (e) {
          this.$emit('change',e.target.innerText)
        },
        handleTouchStart () {
          this.touchStatus = true
        },
        handleTouchMove (e) {
          if(this.touchStatus){
            if(this.timer) {
              clearTimeout(this.timer)
            }
            this.timer = setTimeout(()=> {
              const touchY = e.touches[0].clientY -79
              const index = Math.floor((touchY-this.startY) / 20)
              if(index >= 0 && index < this.letters.length) {
                this.$emit('change',this.letters[index])
              }
            }, 16)
          }
        },
        handleTouchEnd () {
          this.touchStatus = false
        }
      }
    }
    </script>
    <style lang="stylus" scoped>
      @import '~styles/varibles.styl'
      .list
        display flex
        flex-direction column
        justify-content center
        position absolute
        top 1.58rem
        right 0
        bottom 0
        width .4rem
        .item
          line-height .4rem
          text-align center
          color $bgColor
    </style>

最后git提交代码到GitHub上

### 搜索功能实现 ###

*  City.vue传值到Search.vue子组件，通过watch监听用户输入，从而修改输入框下面显示的数组
 *  使用v-show判断用户是否输入了数据，从而实现查找到的数组内容区域的显示隐藏
 *   使用v-show判断用户输入的值是否有对应的值，来实现查找到的数组数据的显示和没有查到内容时的提示
 *  还使用了函数节流，让用户在输入后100毫秒再执行，如果用户在100毫秒之间再输入就会把上次的操作清楚掉，增强性能

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvXzkyMTExMA_size_16_color_FFFFFF_t_70 4][]

Search.vue：

<template>
      <div>
        <div class="search">
          <input v-model="keyword" class="search-input" type="text" placeholder="输入城市名或拼音">
        </div>
        <div 
          class="search-content" 
          ref="search"
          v-show="keyword"
        >
          <ul>
            <li 
              class="search-item border-bottom" 
              v-for="item of list"
              :key="item.id"
            >
              {
       {item.name}}
            </li>
            <li class="search-item border-bottom" v-show="hasNoData">
              没有找到匹配数据
            </li>
          </ul>
        </div>
      </div>
     
    </template>
    <script>
    import Bscroll from 'better-scroll'
    export default {
      name:'CitySearch',
      props: {
        cities: Object
      },
      data () {
        return {
          keyword: '',
          list: [],
          timer: null
        }
      },
      computed: {
        hasNoData () {
          return !this.list.length
        }
      },
      watch: {
        keyword () {
          if (this.timer) {
            clearTimeout(this.timer)
          }
          if (!this.keyword) {
            this.list = []
            return 
          }
          this.timer = setTimeout(() => {
            const result = []
            for (let i in this.cities) {
              this.cities[i].forEach((value) => {
                if (value.spell.indexOf(this.keyword) > -1 ||
                  value.name.indexOf(this.keyword) > -1){
                    result.push(value)
                  }
              })
            }
            this.list = result
          },100)
        }
      },
      mounted () {
        this.scroll = new Bscroll(this.$refs.search)
      }
    }
    </script>
    <style lang="stylus" scoped>
      @import '~styles/varibles.styl'
      .search
        height .72rem
        padding 0 .1rem
        background $bgColor
        .search-input
          box-sizing border-box
          width 100%
          height .62rem
          padding 0 .1rem
          line-height .62rem
          text-align center
          border-radius .06rem
          color #666666
      .search-content
        z-index 1
        position absolute
        overflow hidden
        top 1.58rem
        left 0
        right 0
        bottom 0
        background #eee
        .search-item
          line-height .62rem
          padding-left .2rem
          background #ffffff
          color #666
    
    </style>

### 使用Vuex实现数据共享 ###

*  首先创建一个city-vuex的分支，这里需要实现的功能是点击城市列表页面中城市，首页的城市会发生改变
 *  vuex数据框架是vue大型项目的数据传输使用的框架

重要： vuex，我们可以想象成一个仓库，其中有State、Actions、Mutations；State是所有的公用数据都存在State中，组建需要使用公用的数据，直接去调用State就可以了；Actions是我们可以把需要实现异步操作或者是一些比较复杂的同步操作(批量的同步操作)存在Actions中；Mutations是对State同步的修改操作；组件中怎么使用？（1.组件先去调用Actions，紧接着Actions去调用Mutations，然后Motations去修改State中的数据；2.组件直接调用Motations去修改State中的数据）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvXzkyMTExMA_size_16_color_FFFFFF_t_70 5][]

*  在项目中使用，先安装这个vuex
    
        npm install vuex --save
    
    然后在项目中创建这个"仓库区域",我们把它叫做store，并创建index.js文件，最后在main.js中引入这个文件
    
        import Vue from 'vue'
        import Vuex from 'vuex'
        
        Vue.use(Vuex)
        
        export default new Vuex.Store({
          state: {
            city: '成都'
          },
          mutations: {
            changeCity (state, city) {
              state.city = city
            }
          }
        })
    
    在组件中的使用（在List.vue和Search.vue中使用到了，实现效果就是在点击城市列表页的时候，通过调用mutations中的方法来改变State中的数据），对对应的地方绑定handleCityClick()方法并且在methods中定义这个方法
    
        <div 
           class="button-wrapper" 
           v-for="item of hot" 
           :key="item.id"
           @click="handleCityClick(item.name)"
        >
          <div class="button">{
             {item.name}}</div>
        </div>
    
        <div 
           class="item border-bottom" 
           v-for="innerItem of item" 
           :key="innerItem.id"
           @click="handleCityClick(innerItem.name)"
        >
           {
             {innerItem.name}}
        </div>
    
        handleCityClick (city) {
          this.$store.commit('changeCity', city)
          this.$router.push('/')
        }
    
    这个调用mutations中的方法使用的是commit，可以从上面的图看到；这样最简单的使用vuex就完成了

### Vuex的高级使用及localStorage ###

*  上面实现的功能会有问题，就是每次重启应用的时候，选择的城市会重置为State中预设的城市名，为了解决这个问题，在这里就引入了h5中的localStorage本地缓存来实现
    
        import Vue from 'vue'
        import Vuex from 'vuex'
        
        Vue.use(Vuex)
        
        export default new Vuex.Store({
          state: {
            city: localStorage.city || '成都'
          },
          mutations: {
            changeCity (state, city) {
              state.city = city
              localStorage.city = city
            }
          }
        })
    
    改进版（防止用户没有开启本地缓存功能或者是隐身模式）：
    
        import Vue from 'vue'
        import Vuex from 'vuex'
        
        Vue.use(Vuex)
        
        let defaultCity = '上海'
        try {
          if (localStorage.city) {
            defaultCity = localStorage.city
          }
        } catch (e) {}
        
        export default new Vuex.Store({
          state: {
            city: defaultCity
          },
          mutations: {
            changeCity (state, city) {
              state.city = city
              try {
                localStorage.city = city
              } catch (e) {}
            }
          }
        })
    
    最终版（拆分成了state.js和mutations.js）：
    
        // state.js
        let defaultCity = '上海'
        try {
          if (localStorage.city) {
            defaultCity = localStorage.city
          }
        } catch (e) {}
        
        export default {
          city: defaultCity
        }
    
        // mutations.js
        export default{
          changeCity (state, city) {
            state.city = city
            try {
              localStorage.city = city
            } catch (e) {}
          }
        }
    
        // index.js
        import Vue from 'vue'
        import Vuex from 'vuex'
        import state from './state'
        import mutations from './mutations'
        
        Vue.use(Vuex)
        
        export default new Vuex.Store({
          state,
          mutations
        })
    
     
 *  还有个样式问题，就是选择四个字的城市时，顶部会被撑开，直接修改home/components下的Header.vue中的.header-right样式
    
        .header-right
            min-width 1.04rem  //修改的
            padding 0 .1rem    //新增的
            float right
            text-align center
            color #ffffff
    
     
 *  优化代码：使用vuex提供的mapState来简化代码
    
        // home下的Header.vue的js部分
        <script>
        import { mapState } from 'vuex'    //新增
        export default {
          name: 'HomeHeader',
         computed: {                        //计算属性新增的
           ...mapState(['city'])
         }
        }
        </script>
    
    使用：
    
        <router-link to='/city'>
          <div class="header-right">
            {
             {this.city}}            //从this.$store.state.city精简成的this.city
            <i class="iconfont arrow-icon"></i>
          </div>
        </router-link>
    
     city/components中List.vue：
    
        <template>
          <div class="list" ref='wrapper'>
            <div>
              <div class="area">
                <div class="title border-topbottom">当前城市</div>
                <div class="button-list">
                  <div class="button-wrapper">
                    <div class="button">{
             {this.currentCity}}</div>
                  </div>
                </div>
              </div>
              <div class="area">
                <div class="title border-topbottom">热门城市</div>
                <div class="button-list">
                  <div 
                    class="button-wrapper" 
                    v-for="item of hot" 
                    :key="item.id"
                    @click="handleCityClick(item.name)"
                  >
                    <div class="button">{
             {item.name}}</div>
                  </div>
                </div>
              </div>
              <div 
                class="area" 
                v-for="(item,key) of cities" 
                :key="key"
                :ref="key"
              >
                <div class="title border-topbottom">{
             {key}}</div>
                <div class="item-list">
                  <div 
                    class="item border-bottom" 
                    v-for="innerItem of item" 
                    :key="innerItem.id"
                    @click="handleCityClick(innerItem.name)"
                  >
                    {
             {innerItem.name}}
                  </div>
                </div>
              </div>
             </div>
          </div>
        </template>
        
        <script>
        import BScroll from 'better-scroll'
        import { mapState, mapMutations } from 'vuex'
        export default {
          name:'CityList',
          computed: {
           ...mapState({
             currentCity: 'city'  //这里使用的对象，就是把state中的city映射到这个组件的计算属性中这个值
           })
          },
          props: {  
            hot: Array,
            cities: Object,
            letter: String
          },
          methods: {
            handleCityClick (city) {
              // this.$store.commit('changeCity', city) 使用mutations的方法之前的调用
              this.changeCity(city)
              this.$router.push('/')
            },
            ...mapMutations(['changeCity'])   //使用mapMutations来简化mutations中的方法调用
          },
          mounted () {
            this.scroll = new BScroll(this.$refs.wrapper)
          },
          watch: {
            letter () {
              if (this.letter) {
                const element = this.$refs[this.letter][0]
                this.scroll.scrollToElement(element)
              }
            }
          }
        }
        </script>
        <style lang="stylus" scoped>
          @import '~styles/varibles.styl'
          .border-topbottom
            &:before
              border-color #ccc
            &:after
              border-color #ccc
           .border-bottom
            &:before
              border-color #ccc
          .list
            overflow hidden
            position absolute
            top 1.58rem
            left 0
            right 0
            bottom 0
            .title
              line-height .54rem
              background #eee
              padding-left .2rem
              color #666
              font-size .26rem
            .button-list
              padding .1rem .6rem .1rem .1rem
              overflow hidden 
              .button-wrapper
                float left
                width 33.33%
                .button
                  margin .1rem
                  padding .1rem 0
                  text-align center
                  border .02rem solid #ccc
                  border-radius .06rem
            .item-list
            .item
              line-height .76rem
              padding-left .2rem
        </style>
    
    其他的组件一样使用这种方法来精简代码（这里我把之前创建的没有用的文件夹List和组件也删除了）
 *  另外讲一下vuex中的**getter**和**module**，这 **getter**就是store 的计算属性，通过把State中的数据计算后，组件就可以之间调用getter使用；**module**是当由于使用单一状态树，应用的所有状态会集中到一个比较大的对象。当应用变得非常复杂时，store 对象就有可能变得相当臃肿。 为了解决以上问题，Vuex 允许我们将 store 分割成模块（module）。每个模块拥有自己的 state、mutation、action、getter、甚至是嵌套子模块——从上至下进行同样方式的分割

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvXzkyMTExMA_size_16_color_FFFFFF_t_70 6][]

### 使用keep-alive优化页面性能 ###

*  首先创建在GitHub一个city-keepalive的分支
 *  在App.vue中使用<keep-alive>标签
    
        <template>
          <div id="app">
            <keep-alive>
              <router-view/>
              
            </keep-alive>
          </div>
        </template>
        
        <script>
        export default {
          name: 'App'
        }
        </script>
        
        <style></style>
    
    作用是路由的内容加载过一次之后，就把路由中的内容放到内存之中，下次再重新进这个路由时，不需要重新渲染组件
 *  还有逻辑问题，就是在重新选择城市后在Home.vue中需要重新进行Ajax请求，在Home.vue中引入vuex
    
        import { mapState } from 'vuex'
    
     修改getHomeinfo方法，在请求的时候带上state中的city 
    
        getHomeinfo () {
            axios.get('/api/index.json?city=' + this.city)
              .then(this.getHomeinfoSucc)
        },
    
    这样修改后，重新选择城市也不会重新进行Ajax请求，这里就需要用到activated（使用keep-alive才有的钩子函数）使用mounted和activated这两个钩子函数来实现
    
        mounted () {
            this.lastCity = this.city
            this.getHomeinfo()
          },
          activated () {
            if (this.lastCity !== this.city) {
              this.lastCity = this.city
              this.getHomeinfo()
            }
          }
    
    最后把代表提交到GitHub上

[better-scroll_GitHub]: https://github.com/ustbhuangyi/better-scroll
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