ShowWhen

用来表示某平台或者某屏幕方向时时显示该元素。

<div showWhen="android">
 I am visible on Android!
</div>
<div showWhen="ios">
 I am visible on iOS!
</div>
<div showWhen="android,ios">
 I am visible on Android and iOS!
</div>
<div showWhen="portrait">
 I am visible on Portrait!
</div>
<div showWhen="landscape">
 I am visible on Landscape!
</div>