小程序如何自定义tabbar组件，实现底部tab切换

<view>  <view>    <image></image>    <view>{{item.text}}</view>  </view></view>

Component({  data: {    selected: 0,    color: "#999999",    selectedColor: "#032F82",    list: [      {      type: 'text',      text: "首页"    },     {      type: 'image',      icon: '../../image/icon_map.png',      iconSelect: '../../image/icon_map_select.png',      text: ''    },     {      type: 'text',      text: "我的"    }]  },  attached() {  },  methods: {    switchTab(e) {      const data = e.currentTarget.dataset      this.setData({selected: data.index})      this.triggerEvent("setTab", data.index)    }  }})

.jtab-bar {  position: fixed;  bottom: 0;  left: 0;  right: 0;  height: 100rpx;  background: white;  display: flex;  align-items: center;  padding-bottom: env(safe-area-inset-bottom);  box-shadow: 0px -2rpx 2rpx rgba(153, 153, 153, 0.1);}.jtab-bar-item {  text-align: center;  flex: 1;  height: 100rpx;}.jtab-bar-item .jtab-text {  height: 100rpx;  line-height: 100rpx;}.jcover-img-bigicon {  position: fixed;  bottom: 0rpx;  width: 210rpx;  height: 128rpx;  padding-bottom: env(safe-area-inset-bottom);  margin: 0 auto;  right: 0;  left: 0;}

<view>  <swiper>        <block>          <swiper-item>            <view>{{item}}</view>          </swiper-item>        </block>      </swiper>  <jtabbar></jtabbar></view>

.jswipper-block {  height: calc(100vh - 170rpx);  background: #F7F8F9;}

/**   * 页面的初始数据   */  data: {    background: ['demo-text-1', 'demo-text-2', 'demo-text-3'],    currentTab: 0  },  setTabbar({detail}) {    this.setData({currentTab: detail})  },  // 轮播图 禁止手动滑动 catchtouchmove="swipperStop"  swipperStop(){  },