perf[Sidebar]: optimize code logic (#1349)

Author: AimWhy

src/views/layout/components/Sidebar/SidebarItem.vue

@@ -1,36 +1,25 @@
 <template>
-  <div v-if="!item.hidden&&item.children" class="menu-wrapper">
+  <div v-if="!item.hidden" class="menu-wrapper">
 
     <template v-if="hasOneShowingChild(item.children,item) && (!onlyOneChild.children||onlyOneChild.noShowingChildren)&&!item.alwaysShow">
       <app-link :to="resolvePath(onlyOneChild.path)">
         <el-menu-item :index="resolvePath(onlyOneChild.path)" :class="{'submenu-title-noDropdown':!isNest}">
-          <item v-if="onlyOneChild.meta" :icon="onlyOneChild.meta.icon||item.meta.icon" :title="generateTitle(onlyOneChild.meta.title)" />
+          <item v-if="onlyOneChild.meta" :icon="onlyOneChild.meta.icon||(item.meta&&item.meta.icon)" :title="generateTitle(onlyOneChild.meta.title)" />
         </el-menu-item>
       </app-link>
     </template>
 
     <el-submenu v-else ref="subMenu" :index="resolvePath(item.path)">
       <template slot="title">
-        <item v-if="item.meta" :icon="item.meta.icon" :title="generateTitle(item.meta.title)" />
-      </template>
-
-      <template v-for="child in item.children">
-        <template v-if="!child.hidden">
-          <sidebar-item
-            v-if="child.children&&child.children.length>0"
-            :is-nest="true"
-            :item="child"
-            :key="child.path"
-            :base-path="resolvePath(child.path)"
-            class="nest-menu" />
-
-          <app-link v-else :to="resolvePath(child.path)" :key="child.name">
-            <el-menu-item :index="resolvePath(child.path)">
-              <item v-if="child.meta" :icon="child.meta.icon" :title="generateTitle(child.meta.title)" />
-            </el-menu-item>
-          </app-link>
-        </template>
+        <item v-if="item.meta" :icon="item.meta && item.meta.icon" :title="generateTitle(item.meta.title)" />
       </template>
+      <sidebar-item
+        v-for="child in item.children"
+        :is-nest="true"
+        :item="child"
+        :key="child.path"
+        :base-path="resolvePath(child.path)"
+        class="nest-menu" />
     </el-submenu>
 
   </div>
@@ -70,7 +59,7 @@ export default {
     return {}
   },
   methods: {
-    hasOneShowingChild(children, parent) {
+    hasOneShowingChild(children = [], parent) {
       const showingChildren = children.filter(item => {
         if (item.hidden) {
           return false