提交初始版本，使用vant ui库

miniprogram_npm/@vant/weapp/dropdown-menu/index.wxml

@@ -0,0 +1,23 @@
+<wxs src="../wxs/utils.wxs" module="utils" />
+<wxs src="./index.wxs" module="computed" />
+
+<view class="van-dropdown-menu van-dropdown-menu--top-bottom custom-class">
+  <view
+    wx:for="{{ itemListData }}"
+    wx:key="index"
+    data-index="{{ index }}"
+    class="{{ utils.bem('dropdown-menu__item', { disabled: item.disabled }) }}"
+    bind:tap="onTitleTap"
+  >
+    <view
+      class="{{ item.titleClass }} {{ utils.bem('dropdown-menu__title', { active: item.showPopup, down: item.showPopup === (direction === 'down') }) }} title-class"
+      style="{{ item.showPopup ? 'color:' + activeColor : '' }}"
+    >
+      <view class="van-ellipsis">
+        {{ computed.displayTitle(item) }}
+      </view>
+    </view>
+  </view>
+
+  <slot />
+</view>