## Affix

Fix the element to a specific visible area.

### Basic usage

Affix is fixed at the top of the page by default.

:::demo You can set `offset` attribute to change the offset top，the default value is 0。

```html
<el-affix :offset="120">
  <el-button type="primary">Offset top 120px</el-button>
</el-affix>
```

:::

### Target container

You can set `target` attribute to keep the affix in the container at all times. It will be hidden if out of range.

:::demo Please notice that the container avoid having scrollbar.

```html
<div class="affix-container">
  <el-affix target=".affix-container" :offset="80">
    <el-button type="primary">Target container</el-button>
  </el-affix>
</div>
```

:::

### Fixed position

The affix component provides two fixed positions: `top` and `bottom`.

:::demo You can set `position` attribute to change the fixed position, the default value is `top`.

```html
<el-affix position="bottom" :offset="20">
  <el-button type="primary">Offset bottom 20px</el-button>
</el-affix>
```

:::

### Attributes

| Attribute | Description                     | Type   | Accepted Values | Default |
| --------- | ------------------------------- | ------ | --------------- | ------- |
| offset    | offset distance                 | number | —               | 0       |
| position  | position of affix               | string | top / bottom    | top     |
| target    | target container (CSS selector) | string | —               | —       |
| z-index   | z-index of affix                | number | —               | 100     |

### Events

| Event Name | Description                       | Parameters                 |
| ---------- | --------------------------------- | -------------------------- |
| change     | triggers when fixed state changed | (value: boolean)           |
| scroll     | triggers when scrolling           | scroll top and fixed state |

### Methods

| Method | Description                 | Parameters |
| ------ | --------------------------- | ---------- |
| update | update affix state manually | —          |