提交工程，小程序源码已完成，单片机待完成

wex_small/miniprogram_npm/@vant/weapp/dropdown-menu/index.wxs

@@ -0,0 +1,16 @@
+/* eslint-disable */
+function displayTitle(item) {
+  if (item.title) {
+    return item.title;
+  }
+
+  var match = item.options.filter(function(option) {
+    return option.value === item.value;
+  });
+  var displayTitle = match.length ? match[0].text : '';
+  return displayTitle;
+}
+
+module.exports = {
+  displayTitle: displayTitle
+};