1．type、size和plain属性

设置button的type、size和plain属性的代码

<view style='padding:20px;'>
  <view class='button-group'>
    <!-- size 为default默认大小 -->
    <button type="default">default</button>
    <button type="primary">default</button>
    <button type="warn">default</button>
  </view>
  <view class='button-group'>
    <!-- 设置为镂空按钮 -->
    <button type="default" plain>default</button>
    <button type="primary" plain>default</button>
    <button type="warn" plain>default</button>
  </view>
  <view class='button-group'>
    <!-- size 为mini小尺寸大小 -->
    <button type="default" size="mini">default</button>
    <button type="primary" size="mini">default</button>
    <button type="warn" size="mini">default</button>
  </view>
</view>