vant/docs/src/components/MobileNav.vue

<template>
  <div class="mobile-nav-group">
    <div
      class="mobile-nav-group__title mobile-nav-group__basetitle"
      :class="{
        'mobile-nav-group__title--open': isOpen
      }"
      @click="handleNavTitleClick">
      {{ group.groupName }}
    </div>
    <div class="mobile-nav-group__list-wrapper" :class="{ 'mobile-nav-group__list-wrapper--open': isOpen }">
      <ul class="mobile-nav-group__list" :class="{ 'mobile-nav-group__list--open': isOpen }">
        <template v-for="(navItem, index) in group.list">
          <li
            :key="index"
            class="mobile-nav-group__title"
            v-if="!navItem.disabled">
            <router-link
              active-class="active"
              :to="'/' + base + navItem.path">
              <p>
                {{ navItem.title }}
              </p>
            </router-link>
            <van-icon name="arrow" />
          </li>
        </template>
      </ul>
    </div>
  </div>
</template>

<script>
export default {
  props: {
    group: {
      type: Object,
      default: () => {
        return [];
      }
    },
    base: String,
    navKey: [String, Number]
  },

  data() {
    return {
      isOpen: false
    };
  },

  mounted() {
    this.isOpen = JSON.parse(sessionStorage.getItem('mobile-nav-' + this.navKey));
  },

  methods: {
    handleNavTitleClick() {
      this.isOpen = !this.isOpen;
      sessionStorage.setItem('mobile-nav-' + this.navKey, this.isOpen);
    }
  }
};
</script>

<style lang="postcss">
.mobile-nav-group {
  border-radius: 2px;
  margin-bottom: 15px;
  background-color: #fff;
  box-shadow: 0 1px 1px 0 rgba(0,0,0,0.10);

  &__basetitle {
    padding-left: 20px;
  }

  &__title {
    font-size: 16px;
    color: #333;
    line-height: 56px;
    position: relative;
    user-select: none;

    &:active {
      background-color: $active-color;
    }

    &--open {
      color: #999;
    }

    a {
      color: #333;
      display: block;
      user-select: none;
      padding-left: 20px;
      -webkit-tap-highlight-color: rgba(0, 0, 0, 0);

      &:active {
        background: #ECECEC;
      }

      > p {
        margin: 0;
        border-top: 1px solid #e5e5e5;
      }
    }

    .van-icon-arrow {
      position: absolute;
      font-size: 12px;
      line-height: 1;
      top: 24px;
      right: 20px;
    }
  }

  &__list-wrapper {
    height: 0;
    overflow: hidden;

    &--open {
      height: auto;
    }
  }

  &__list {
    transform: translateY(-50%);
    transition: transform .2s ease-out;

    &--open {
      transform: translateY(0);
    }
  }

  li {
    list-style: none;
  }

  ul {
    padding: 0;
    margin: 0;
    overflow: hidden;
  }
}
</style>