<a name="tab"></a>
## tab(selector, [options])
tab tab導航欄
**Kind**: global function
| Param | Type | Default | Description |
| --- | --- | --- | --- |
| selector | <code>string</code> | | tab的selector |
| [options] | <code>object</code> | | 配置項 |
| [options.defaultIndex] | <code>number</code> | <code>0</code> | 初始展示的index |
| [options.onChange] | <code>function</code> | | 點擊tab時，返回對應的index |
**Example**
#### html
```html
<div class="weui-tab" id="tab">
<div class="weui-navbar">
<div class="weui-navbar__item">反饋</div>
<div class="weui-navbar__item">表單</div>
<div class="weui-navbar__item">上傳</div>
<div class="weui-navbar__item">其它</div>
</div>
<div class="weui-tab__panel">
<div class="weui-tab__content">反饋頁</div>
<div class="weui-tab__content">表單頁</div>
<div class="weui-tab__content">上傳頁</div>
<div class="weui-tab__content">其它頁</div>
</div>
</div>
```
#### js
```javascript
weui.tab('#tab',{
defaultIndex: 0,
onChange: function(index){
console.log(index);
}
});
```
