来源：https://ui.docs.xihanfun.com/en/components/affix

# Affix

Navigation component. This page is the API reference, generated from the source code. Usage guidance and live examples are on the [Chinese page](/components/affix).

<div class="xh-resource-links">
  <a href="https://github.com/XiHanFun/XiHan.UI/tree/dev/ui/packages/engine/headless/src/affix" target="_blank" rel="noreferrer">Headless</a>
  <a href="https://github.com/XiHanFun/XiHan.UI/blob/dev/ui/packages/design/styles/css/affix.css" target="_blank" rel="noreferrer">Styles</a>
  <a href="https://github.com/XiHanFun/XiHan.UI/tree/dev/ui/packages/adapters/vue/src/components/affix" target="_blank" rel="noreferrer">Vue</a>
  <a href="https://github.com/XiHanFun/XiHan.UI/tree/dev/ui/packages/adapters/react/src/components/affix" target="_blank" rel="noreferrer">React</a>
  <a href="https://github.com/XiHanFun/XiHan.UI/blob/dev/ui/packages/adapters/web-components/src/elements/affix.ts" target="_blank" rel="noreferrer">Web Components</a>
</div>

## Anatomy

Parts in bold are required.

`data-scope="affix"`: **`root`** · **`content`**

## API reference

Descriptions of individual props, events and slots are written in Chinese and appear on the Chinese page.

### Artifacts

| Layer | Value |
| --- | --- |
| Custom element | `<xh-affix>` |
| Vue components | `XhAffixContent` `XhAffixRoot` |
| Composable | `useAffix` |
| State machine | `affixMachine` |
| Skin | `@xihan-ui/styles/affix.css` |

### Props

| Prop | Type | Required |
| --- | --- | --- |
| `offsetTop` | `number` |  |
| `offsetBottom` | `number` |  |
| `onAffixChange` | `(details: AffixChangeDetails) => void` |  |

### Events

Custom elements put the payload in `detail`; Vue emits an event of the same name.

| Event | Payload |
| --- | --- |
| `affix-change` | `AffixChangeDetails` |

### Slots

Only slots with a payload are listed.

| Vue component | Slot | Payload |
| --- | --- | --- |
| `XhAffixRoot` | `default` | `AffixRootSlotProps` |

### React adapter props

Only the props each component declares itself: DOM attributes inherited from `ComponentPropsWithRef` are left out, and root props already listed in the Props table are not repeated. The Vue counterpart is the slot table above.

| React component | Prop | Type | Required |
| --- | --- | --- | --- |
| `XhAffixRoot` | `target` | `() => HTMLElement \| null` |  |
| `XhAffixRoot` | `children` | `SlotChildren<AffixRootSlotProps>` |  |

### State

The following names are internal to the state machine.

**States**: `released` · `affixed`

**Events**: `SCROLL.RESOLVE`

**Guards**: `shouldAffix` · `shouldRelease`

### connect API

`getXxxProps()` returns the host attributes of the matching part.

| Member | Type |
| --- | --- |
| `affixed` | `boolean` |
| `getRootProps` | `() => T['element']` |
| `getContentProps` | `() => T['element']` |

## Accessibility

### Keyboard

Specification: [W3C APG](https://www.w3.org/WAI/ARIA/apg/). Each row is a stable behavior id that the conformance tests cover; the conditions and effects are described on the Chinese page.

No keyboard interaction: the component takes no focus, or focus behavior comes entirely from native elements.

## Style reference

### Skin

`@xihan-ui/styles/affix.css` is written against `[data-scope="affix"][data-part="root"]` part selectors; the published build uses the mount class `.xh-scope-affix` in place of data-scope (same specificity) and sits in the `xihan.components` layer. Put overrides in `xihan.overrides`; the part selectors work as usual.

### Data attributes

Produced by `connect`; valueless attributes are omitted while their condition does not hold.

| Part | Attribute | Value |
| --- | --- | --- |
| `content` | `data-fixed` | '' (present only while the condition holds) |

### CSS variables

The public override slots, generated from what the standalone skin actually consumes.

| Variable | Part | CSS property | State | Default from |
| --- | --- | --- | --- | --- |
| `--xh-affix-layer` | `content` | `z-index` | `fixed` | `--xh-layer-sticky` |