feat: 更新 eslint 后，修复新检查出的错误

src/views/demo/playground/add-routes/routes.vue

@@ -81,7 +81,7 @@ export default {
         ...route
       ])
       // 演示更新菜单
-      let menuGroup = {
+      const menuGroup = {
         title: '临时菜单',
         icon: 'plus-square',
         children: []
@@ -91,7 +91,7 @@ export default {
         title,
         icon: 'file-o'
       }
-      let header = cloneDeep(this.header)
+      const header = cloneDeep(this.header)
       const menuGroupIndex = header.findIndex(e => e.title === menuGroup.title)
       // 如果顶栏菜单已经有这个组，就在组里添加项目，反之新建一个菜单组
       if (menuGroupIndex >= 0) {

src/views/demo/playground/db/page-snapshot-public/index.vue

@@ -88,7 +88,7 @@ export default {
   async created () {
     const data = await this.pageGet({ instance: this })
     for (const key in data) {
-      if (data.hasOwnProperty(key)) this[key] = data[key]
+      this[key] = data[key]
     }
   },
   watch: {

src/views/demo/playground/db/page-snapshot-user/index.vue

@@ -88,7 +88,7 @@ export default {
   async created () {
     const data = await this.pageGet({ instance: this, user: true })
     for (const key in data) {
-      if (data.hasOwnProperty(key)) this[key] = data[key]
+      this[key] = data[key]
     }
   },
   watch: {