edison1105 · Oct 12, 2026 · Oct 11, 2026 · Oct 12, 2026
diff --git a/packages/runtime-vapor/__tests__/componentAttrs.spec.ts b/packages/runtime-vapor/__tests__/componentAttrs.spec.ts
@@ -3370,7 +3370,7 @@ describe('attribute fallthrough', () => {
       'constructor',
       'value',
     ]) {
-      expect(attrs[key]).toBeUndefined()
+      expect(attrs[key]).toBe((Object.prototype as any)[key])
       expect(key in attrs).toBe(false)
     }
     expect(Object.keys(attrs)).toEqual(['title'])
@@ -3509,3 +3509,47 @@ describe('checkbox model value bindings', () => {
     )
   })
 })
+
+test('attrs object supports hasOwnProperty like vdom', async () => {
+  const { vdom, vapor } = await renderParity(
+    {
+      Comp: `<script setup>
+        import { useAttrs } from 'vue'
+        const attrs = useAttrs()
+      </script>
+      <template><p>{{ attrs.hasOwnProperty('id') }}-{{ $attrs.hasOwnProperty('title') }}-{{ attrs.hasOwnProperty('missing') }}</p></template>`,
+      App: `<template><components.Comp v-bind="data" /></template>`,
+    },
+    () => ref<any>({ id: 'a', title: 't' }),
+    async (data, root) => {
+      expect(root.textContent).toBe('true-true-false')
+      data.value = { id: 'a' }
+    },
+  )
+  expect(vdom.text).toBe('true-false-false')
+  expect(vapor.after).toBe(vdom.after)
+})
+
+test('attrs with an undefined value shadow Object.prototype until removed', async () => {
+  const { vdom, vapor } = await renderParity(
+    {
+      Comp: `<script setup>
+        import { useAttrs } from 'vue'
+        defineOptions({ inheritAttrs: false })
+        const attrs = useAttrs()
+      </script>
+      <template><p>{{ attrs.toString === undefined }}-{{ attrs.toString === Object.prototype.toString }}</p></template>`,
+      App: `<template><components.Comp v-bind="data" /></template>`,
+    },
+    () => ref<any>({}),
+    async (data, root) => {
+      expect(root.textContent).toBe('false-true')
+      data.value = { toString: undefined }
+      await nextTick()
+      expect(root.textContent).toBe('true-false')
+      data.value = {}
+    },
+  )
+  expect(vdom.text).toBe('false-true')
+  expect(vapor.after).toBe(vdom.after)
+})
diff --git a/packages/runtime-vapor/__tests__/componentProps.spec.ts b/packages/runtime-vapor/__tests__/componentProps.spec.ts
@@ -2779,3 +2779,19 @@ describe('component: fallthrough props parity', () => {
     },
   )
 })
+
+test('props object supports hasOwnProperty like vdom', async () => {
+  const { vdom, vapor } = await renderParity(
+    {
+      Comp: `<script setup>
+        const props = defineProps(['foo', 'bar', 'constructor'])
+      </script>
+      <template><p>{{ props.hasOwnProperty('foo') }}-{{ props.hasOwnProperty('bar') }}-{{ props.hasOwnProperty('baz') }}-{{ props.hasOwnProperty('constructor') }}-{{ props.constructor === undefined }}</p></template>`,
+      App: `<template><components.Comp foo="1" baz="2" :constructor="undefined" /></template>`,
+    },
+    () => ref(null),
+    () => {},
+  )
+  expect(vdom.text).toBe('true-true-false-true-true')
+  expect(vapor.after).toBe(vdom.after)
+})
diff --git a/packages/runtime-vapor/__tests__/componentSlots.spec.ts b/packages/runtime-vapor/__tests__/componentSlots.spec.ts
@@ -8384,3 +8384,35 @@ test('caches native dynamic slot descriptors across reads', async () => {
     app.unmount()
   }
 })
+
+test.each(['id="a"', 'v-bind="data"'])(
+  'scoped slot props support hasOwnProperty like vdom (%s)',
+  async binding => {
+    const { vdom, vapor } = await renderParity(
+      {
+        Comp: `<template><slot ${binding} /></template>`,
+        App: `<template><components.Comp v-slot="props"><p>{{ props.hasOwnProperty('id') }}-{{ props.hasOwnProperty('missing') }}-{{ props.hasOwnProperty('toString') }}-{{ Object.keys(props).join(',') }}</p></components.Comp></template>`,
+      },
+      () => ref({ id: 'a' }),
+      () => {},
+    )
+    expect(vdom.text).toBe('true-false-false-id')
+    expect(vapor.text).toBe(vdom.text)
+  },
+)
+
+test('scoped slot props with an undefined value shadow Object.prototype', async () => {
+  const { vdom, vapor } = await renderParity(
+    {
+      Comp: `<template><slot v-bind="data" /></template>`,
+      App: `<template><components.Comp v-slot="props"><p>{{ props.toString === undefined }}-{{ props.toString === Object.prototype.toString }}</p></components.Comp></template>`,
+    },
+    () => ref<any>({ toString: undefined }),
+    (data, root) => {
+      expect(root.textContent).toBe('true-false')
+      data.value = {}
+    },
+  )
+  expect(vdom.text).toBe('false-true')
+  expect(vapor.text).toBe(vdom.text)
+})
diff --git a/packages/runtime-vapor/__tests__/vdomInterop.spec.ts b/packages/runtime-vapor/__tests__/vdomInterop.spec.ts
@@ -14153,3 +14153,74 @@ describe('vdom component template refs', () => {
     expect(seen.vapor).toEqual(seen.vdom)
   })
 })
+
+test.each([true, false])(
+  'props and attrs support hasOwnProperty (parent vapor: %s)',
+  async vapor => {
+    const data = ref<any>({ id: 'a' })
+    const Comp = compile(
+      `<script setup>
+        import { useAttrs } from 'vue'
+        defineOptions({ inheritAttrs: false })
+        const props = defineProps(['foo', 'bar'])
+        const attrs = useAttrs()
+      </script>
+      <template><p>{{ props.hasOwnProperty('foo') }}-{{ props.hasOwnProperty('bar') }}-{{ attrs.hasOwnProperty('id') }}-{{ attrs.hasOwnProperty('constructor') }}</p></template>`,
+      data,
+      {},
+      { vapor: !vapor },
+    )
+    const App = compile(
+      `<script setup>
+        const data = _data
+        const components = _components
+      </script>
+      <template><components.Comp foo="1" v-bind="data" /></template>`,
+      data,
+      { Comp },
+      { vapor },
+    )
+    const { host, app } = define(App).render()
+    try {
+      expect(host.textContent).toBe('true-true-true-false')
+      data.value = {}
+      await nextTick()
+      expect(host.textContent).toBe('true-true-false-false')
+    } finally {
+      app.unmount()
+    }
+  },
+)
+
+test.each([true, false])(
+  'scoped slot props support hasOwnProperty (parent vapor: %s)',
+  async vapor => {
+    const data = ref<any>({ id: 'a' })
+    const Comp = compile(
+      `<script setup>const data = _data</script>
+      <template><slot v-bind="data" /></template>`,
+      data,
+      {},
+      { vapor: !vapor },
+    )
+    const App = compile(
+      `<script setup>const components = _components</script>
+      <template><components.Comp v-slot="props"><p>{{ props.hasOwnProperty('id') }}-{{ props.hasOwnProperty('toString') }}-{{ props.toString === undefined }}</p></components.Comp></template>`,
+      data,
+      { Comp },
+      { vapor },
+    )
+    const { host, app } = define(App).render()
+    try {
+      expect(host.textContent).toBe('true-false-false')
+      data.value = { id: 'a', toString: undefined }
+      await nextTick()
+      expect(host.textContent).toBe('true-true-true')
+      data.value = {}
+      await nextTick()
+      expect(host.textContent).toBe('false-false-false')
+    } finally {
+      app.unmount()
+    }
+  },
+)
diff --git a/packages/runtime-vapor/src/componentProps.ts b/packages/runtime-vapor/src/componentProps.ts
@@ -244,6 +244,8 @@ export function getPropsProxyHandlers(
       trackPropsValue(instance, key)
       return instance.propsValues[key]
     }
+    // fall back to Object.prototype so `props.hasOwnProperty()` works like vdom
+    return (Object.prototype as any)[key]
   }
 
   const propsHandlers = propsOptions
@@ -273,8 +275,10 @@ export function getPropsProxyHandlers(
   const getAttr = (instance: VaporComponentInstance, key: string | symbol) => {
     if (isAttr(key)) {
       trackPropsValue(instance, key)
-      return instance.propsValues[key]
+      if (hasOwn(instance.propsValues, key)) return instance.propsValues[key]
     }
+    // fall back to Object.prototype so `attrs.hasOwnProperty()` works like vdom
+    return (Object.prototype as any)[key]
   }
   const hasAttr = (instance: VaporComponentInstance, key: string | symbol) => {
     if (!isAttr(key)) return false
@@ -347,6 +351,7 @@ export function getAttrFromRawProps(rawProps: RawProps, key: string): unknown {
     merged.reverse()
     return isEvent ? merged.reduce(mergeEventHandlers) : merged
   }
+  return (Object.prototype as any)[key]
 }
 
 function mergeEventHandlers(existing: unknown, incoming: unknown): unknown {

diff --git a/packages/runtime-vapor/src/vdomInterop.ts b/packages/runtime-vapor/src/vdomInterop.ts
@@ -126,6 +126,7 @@ import {
   ShapeFlags,
   VaporSlotFlags,
   extend,
+  hasOwn,
   isArray,
   isForwardedSlot,
   isFunction,
@@ -1017,7 +1018,7 @@ const vaporSlotPropsProxyHandler: ProxyHandler<
     return Reflect.ownKeys(target.value)
   },
   getOwnPropertyDescriptor(target, key: any) {
-    if (key in target.value) {
+    if (hasOwn(target.value, key)) {
       return {
         enumerable: true,
         configurable: true,