refactor: fix eslint warnings in the cli-ui codebase

packages/@vue/cli-ui/src/components/content/TerminalView.vue

@@ -213,7 +213,7 @@ export default {
         if (emptySelection) {
           this.$_terminal.selectAll()
         }
-        var selection = this.$_terminal.getSelection()
+        const selection = this.$_terminal.getSelection()
         textarea.value = selection
         textarea.select()
         document.execCommand('copy')

packages/@vue/cli-ui/src/components/dashboard/Widget.vue

@@ -24,8 +24,7 @@
               <!-- Custom actions -->
               <template v-if="widget.configured">
                 <VueButton
-                  v-for="action of headerActions"
-                  v-if="!action.hidden"
+                  v-for="action of visibleHeaderActions"
                   :key="action.id"
                   :icon-left="action.icon"
                   :disabled="action.disabled"
@@ -296,6 +295,10 @@ export default {
         return this.widget.definition.detailsComponent
       }
       return this.widget.definition.component
+    },
+
+    visibleHeaderActions () {
+      return this.headerActions.filter(action => !action.hidden)
     }
   },
 

packages/@vue/cli-ui/src/components/dashboard/WidgetAddPane.vue

@@ -34,12 +34,13 @@
         />
 
         <template v-else-if="data">
-          <WidgetAddItem
-            v-for="definition of data.widgetDefinitions.filter(filterDefinition)"
-            v-if="definition.canAddMore"
-            :key="definition.id"
-            :definition="definition"
-          />
+          <template v-for="definition of data.widgetDefinitions.filter(filterDefinition)">
+            <WidgetAddItem
+              v-if="definition.canAddMore"
+              :key="definition.id"
+              :definition="definition"
+            />
+          </template>
         </template>
       </template>
     </ApolloQuery>

packages/@vue/cli-ui/src/components/file-diff/FileDiffChange.vue

@@ -45,6 +45,8 @@ export default {
       } else if (this.change.type === 'del') {
         return this.change.ln
       }
+
+      return ''
     },
 
     ln2 () {
@@ -53,6 +55,8 @@ export default {
       } else if (this.change.type === 'add') {
         return this.change.ln
       }
+
+      return ''
     }
   },
 

packages/@vue/cli-ui/src/components/folder/FolderExplorer.vue

@@ -146,13 +146,14 @@
         />
       </transition>
       <template v-if="folderCurrent && folderCurrent.children">
-        <FolderExplorerItem
-          v-for="folder of folderCurrent.children"
-          v-if="showHidden || !folder.hidden"
-          :key="folder.name"
-          :folder="folder"
-          @select="openFolder(folder.path)"
-        />
+        <template v-for="folder of folderCurrent.children">
+          <FolderExplorerItem
+            v-if="showHidden || !folder.hidden"
+            :key="folder.name"
+            :folder="folder"
+            @select="openFolder(folder.path)"
+          />
+        </template>
       </template>
     </div>
 

packages/@vue/cli-ui/src/components/prompt/PromptsList.vue

@@ -8,14 +8,15 @@
       >
         <div v-if="group.id" class="group-name">{{ $t(group.id) }}</div>
 
-        <component
-          v-for="prompt of group.prompts"
-          v-if="prompt.visible"
-          :key="prompt.id"
-          :is="getModule(prompt)"
-          :prompt="prompt"
-          @answer="value => $emit('answer', { prompt, value })"
-        />
+        <template v-for="prompt of group.prompts">
+          <component
+            v-if="prompt.visible"
+            :key="prompt.id"
+            :is="getModule(prompt)"
+            :prompt="prompt"
+            @answer="value => $emit('answer', { prompt, value })"
+          />
+        </template>
       </div>
 
       <div v-if="!prompts.length" class="vue-ui-empty">

packages/@vue/cli-ui/src/components/view/ViewNav.vue

@@ -15,12 +15,13 @@
         class="vertical small-indicator left-indicator primary"
         indicator
       >
-        <ViewNavButton
-          v-for="view of views"
-          v-if="hasProjectType(view)"
-          :key="view.id"
-          :view="view"
-        />
+        <template v-for="view of views">
+          <ViewNavButton
+            v-if="hasProjectType(view)"
+            :key="view.id"
+            :view="view"
+          />
+        </template>
       </VueGroup>
 
       <ViewNavMore/>

packages/@vue/cli-ui/src/components/view/ViewNavButton.vue

@@ -66,6 +66,8 @@ export default {
       if (this.view.badges && this.view.badges.length) {
         return this.view.badges.slice().sort((a, b) => b.priority - a.priority)
       }
+
+      return []
     },
 
     firstNotHiddenBadge () {