fix(NavigationMenu): correct item-content and item-trailing slot behavior

docs/content/docs/2.components/navigation-menu.md

@@ -1340,6 +1340,10 @@ You can also use the `#item`, `#item-leading`, `#item-label`, `#item-trailing` a
 
 Use the `#item-trailing` slot or the `slot` property (`#{{ item.slot }}-trailing`) to add a [DropdownMenu](/docs/components/dropdown-menu) that appears on hover, similar to Notion or Linear.
 
+::note
+When you pass `#item-trailing` (or `#{{ item.slot }}-trailing`), it replaces the default trailing UI for every item (badge and chevron). Use the slot props (`item`, `active`, etc.) to render different content per row.
+::
+
 ::component-example
 ---
 collapse: true
@@ -1351,6 +1355,10 @@ name: 'navigation-menu-trailing-slot-example'
 
 Use the `#item-content` slot or the `slot` property (`#{{ item.slot }}-content`) to customize the content of a specific item.
 
+::note
+In **horizontal** orientation, the menu trigger and panel are only rendered for items that define a `children` array. The `#item-content` slot customizes what appears inside that panel, it does not create a dropdown for items without `children`.
+::
+
 ::component-example
 ---
 collapse: true

src/runtime/components/NavigationMenu.vue

@@ -366,13 +366,16 @@ function onLinkTrailingClick(e: Event, item: NavigationMenuItem) {
 
       <component
         :is="orientation === 'vertical' && item.children?.length && !collapsed ? AccordionTrigger : 'span'"
-        v-if="(item.badge || item.badge === 0) || (orientation === 'horizontal' && (item.children?.length || !!slots[(item.slot ? `${item.slot}-content` : 'item-content') as keyof NavigationMenuSlots<T>])) || (orientation === 'vertical' && item.children?.length) || item.trailingIcon || !!slots[(item.slot ? `${item.slot}-trailing` : 'item-trailing') as keyof NavigationMenuSlots<T>]"
+        v-if="(item.badge || item.badge === 0) || (orientation === 'horizontal' && item.children?.length) || (orientation === 'vertical' && item.children?.length) || item.trailingIcon || !!slots[(item.slot ? `${item.slot}-trailing` : 'item-trailing') as keyof NavigationMenuSlots<T>]"
         :as="orientation === 'vertical' && item.children?.length && !collapsed ? 'span' : undefined"
         data-slot="linkTrailing"
         :class="ui.linkTrailing({ class: [uiProp?.linkTrailing, item.ui?.linkTrailing] })"
         @click="(e: Event) => onLinkTrailingClick(e, item)"
       >
-        <slot :name="((item.slot ? `${item.slot}-trailing` : 'item-trailing') as keyof NavigationMenuSlots<T>)" :item="item" :active="active" :index="index" :ui="ui">
+        <template v-if="!!slots[(item.slot ? `${item.slot}-trailing` : 'item-trailing') as keyof NavigationMenuSlots<T>]">
+          <slot :name="((item.slot ? `${item.slot}-trailing` : 'item-trailing') as keyof NavigationMenuSlots<T>)" :item="item" :active="active" :index="index" :ui="ui" />
+        </template>
+        <template v-else>
           <UBadge
             v-if="item.badge || item.badge === 0"
             color="neutral"
@@ -383,9 +386,9 @@ function onLinkTrailingClick(e: Event, item: NavigationMenuItem) {
             :class="ui.linkTrailingBadge({ class: [uiProp?.linkTrailingBadge, item.ui?.linkTrailingBadge] })"
           />
 
-          <UIcon v-if="(orientation === 'horizontal' && (item.children?.length || !!slots[(item.slot ? `${item.slot}-content` : 'item-content') as keyof NavigationMenuSlots<T>])) || (orientation === 'vertical' && item.children?.length)" :name="item.trailingIcon || trailingIcon || appConfig.ui.icons.chevronDown" data-slot="linkTrailingIcon" :class="ui.linkTrailingIcon({ class: [uiProp?.linkTrailingIcon, item.ui?.linkTrailingIcon], active })" />
+          <UIcon v-if="(orientation === 'horizontal' && item.children?.length) || (orientation === 'vertical' && item.children?.length)" :name="item.trailingIcon || trailingIcon || appConfig.ui.icons.chevronDown" data-slot="linkTrailingIcon" :class="ui.linkTrailingIcon({ class: [uiProp?.linkTrailingIcon, item.ui?.linkTrailingIcon], active })" />
           <UIcon v-else-if="item.trailingIcon" :name="item.trailingIcon" data-slot="linkTrailingIcon" :class="ui.linkTrailingIcon({ class: [uiProp?.linkTrailingIcon, item.ui?.linkTrailingIcon], active })" />
-        </slot>
+        </template>
       </component>
     </slot>
   </DefineLinkTemplate>
@@ -402,7 +405,7 @@ function onLinkTrailingClick(e: Event, item: NavigationMenuItem) {
       </div>
       <ULink v-else-if="item.type !== 'label'" v-slot="{ active, ...slotProps }" v-bind="(orientation === 'vertical' && item.children?.length && !collapsed && item.type === 'trigger') ? {} : pickLinkProps(item as Omit<NavigationMenuItem, 'type'>)" custom>
         <component
-          :is="(orientation === 'horizontal' && (item.children?.length || !!slots[(item.slot ? `${item.slot}-content` : 'item-content') as keyof NavigationMenuSlots<T>])) ? NavigationMenuTrigger : ((orientation === 'vertical' && item.children?.length && !collapsed && !(slotProps as any).href) ? AccordionTrigger : NavigationMenuLink)"
+          :is="(orientation === 'horizontal' && item.children?.length) ? NavigationMenuTrigger : ((orientation === 'vertical' && item.children?.length && !collapsed && !(slotProps as any).href) ? AccordionTrigger : NavigationMenuLink)"
           as-child
           :active="active || item.active"
           :disabled="item.disabled"
@@ -455,7 +458,7 @@ function onLinkTrailingClick(e: Event, item: NavigationMenuItem) {
           </ULinkBase>
         </component>
 
-        <NavigationMenuContent v-if="orientation === 'horizontal' && (item.children?.length || !!slots[(item.slot ? `${item.slot}-content` : 'item-content') as keyof NavigationMenuSlots<T>])" v-bind="contentProps" data-slot="content" :class="ui.content({ class: [uiProp?.content, item.ui?.content] })">
+        <NavigationMenuContent v-if="orientation === 'horizontal' && item.children?.length" v-bind="contentProps" data-slot="content" :class="ui.content({ class: [uiProp?.content, item.ui?.content] })">
           <slot :name="((item.slot ? `${item.slot}-content` : 'item-content') as keyof NavigationMenuSlots<T>)" :item="item" :active="active || item.active" :index="index" :ui="ui">
             <ul data-slot="childList" :class="ui.childList({ class: [uiProp?.childList, item.ui?.childList] })">
               <li v-for="(childItem, childIndex) in item.children" :key="childIndex" data-slot="childItem" :class="ui.childItem({ class: [uiProp?.childItem, item.ui?.childItem] })">

test/components/NavigationMenu.spec.ts

@@ -1,4 +1,5 @@
 import { describe, it, expect, test } from 'vitest'
+import { h } from 'vue'
 import { axe } from 'vitest-axe'
 import { mountSuspended } from '@nuxt/test-utils/runtime'
 import { renderEach } from '../component-render'
@@ -130,6 +131,46 @@ describe('NavigationMenu', () => {
     expect(await axe(wrapper.element)).toHaveNoViolations()
   })
 
+  it('does not treat global item-content slot as a trigger for items without children', async () => {
+    const wrapper = await mountSuspended(NavigationMenu, {
+      props: {
+        orientation: 'horizontal',
+        variant: 'link',
+        items: [[
+          { label: 'NoChildren', to: '/' },
+          { label: 'WithChildren', to: '/', children: [{ label: 'Child', to: '/child' }] }
+        ]]
+      },
+      slots: {
+        'item-content': ({ item }: { item: { children?: unknown[] } }) => h('div', item.children?.length ? 'custom' : '')
+      }
+    })
+
+    // Only the item with `children` uses NavigationMenuTrigger; the slot must not force a trigger on plain links.
+    expect(wrapper.findAll('[data-navigation-menu-trigger]')).toHaveLength(1)
+  })
+
+  it('item-trailing slot fully overrides default trailing icons', async () => {
+    const wrapper = await mountSuspended(NavigationMenu, {
+      props: {
+        orientation: 'horizontal',
+        variant: 'link',
+        items: [[
+          { label: 'NoChildren', to: '/' },
+          { label: 'WithChildren', to: '/', children: [{ label: 'Child', to: '/child' }] }
+        ]]
+      },
+      slots: {
+        'item-trailing': ({ item }: { item: { children?: unknown[] } }) => item.children?.length
+          ? h('span', { 'data-testid': 'custom-trailing' }, 'V')
+          : undefined
+      }
+    })
+
+    expect(wrapper.findAll('[data-slot="linkTrailingIcon"]')).toHaveLength(0)
+    expect(wrapper.findAll('[data-testid="custom-trailing"]')).toHaveLength(1)
+  })
+
   test('should have the correct types', () => {
     // normal
     expectSlotProps('item', () => NavigationMenu({