<view class="hd">
  <!-- 第一层导航 -->
  <view class="firstLevelNavContainer">
    <block wx:for="{{firstLevelNav}}" wx:key="firstLevelNav">
      <view class="firstLevelNavItem {{firstLevelNavType == index ? 'firstLevelNavItem_on' : ''}}"
            catchtap="changeFirstLevelType"
            data-index="{{index}}">
        {{item.name}}
      </view>
    </block>
  </view>

  <!-- 第二层导航 -->
  <view class="secondLevelNavContainer">
    <view class="secondLevelNavRow">
      <block wx:for="{{currentSecondLevelNav}}" wx:key="currentSecondLevelNav">
        <view class="secondLevelNavItem {{secondLevelNavType == index ? 'secondLevelNavItem_on' : ''}}"
              catchtap="changeSecondLevelType"
              data-index="{{index}}">
          {{item}}
        </view>
      </block>
    </view>
  </view>
</view>

page {
  background: #F8F8F8;
  padding-bottom: 20rpx;
}

.hd {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: auto;
  background: #fff;
}

.firstLevelNavContainer {
  height: 88rpx;
  line-height: 88rpx;
  display: flex;
}

.firstLevelNavItem {
  flex: 1;
  text-align: center;
  font-size: 28rpx;
  font-family: PingFang SC;
  font-weight: 500;
  color: #333333;
}

.firstLevelNavItem_on {
  font-size: 30rpx;
  color: #FA871E;
  position: relative;
}

.firstLevelNavItem_on::after {
  content: "";
  position: absolute;
  bottom: 0;
  width: 40%;
  height: 6rpx;
  background: #FA871E;
  border-radius: 3rpx;
  left: 50%;
  transform: translateX(-50%);
}

.secondLevelNavContainer {
  margin-top: 10rpx;
}

.secondLevelNavRow {
  height: 88rpx;
  line-height: 88rpx;
  display: flex;
}

.secondLevelNavItem {
  flex: 1;
  text-align: center;
  font-size: 24rpx;
  font-family: PingFang SC;
  font-weight: 400;
  color: #666666;
}

.secondLevelNavItem_on {
  font-size: 26rpx;
  color: #FA871E;
}

Page({
  data: {
    firstLevelNav: [
      {name: '充值', children: ['充值明细', '充值汇总']},
      {name: '消费', children: ['消费明细', '消费汇总']}
    ],
    firstLevelNavType: 0,
    secondLevelNavType: 0,
    currentSecondLevelNav: [],
  },

  onLoad: function() {
    this.setData({
      currentSecondLevelNav: this.data.firstLevelNav[this.data.firstLevelNavType].children
    });
  },

  changeFirstLevelType: function(e) {
    let index = e.currentTarget.dataset.index;
    if (this.data.firstLevelNavType !== index) {
      this.setData({
        firstLevelNavType: index,
        secondLevelNavType: 0,
        currentSecondLevelNav: this.data.firstLevelNav[index].children
      });
    }
  },

  changeSecondLevelType: function(e) {
    let index = e.currentTarget.dataset.index;
    if (this.data.secondLevelNavType !== index) {
      this.setData({
        secondLevelNavType: index
      });
    }
  },
});```