scroll-view
可滚动视图区域。
| 属性名 | 类型 | 默认值 | 说明 |
| --- | --- | --- | --- |
|scroll-x |Boolean| false |允许横向滚动 |
| scroll-y|Boolean |false |允许纵向滚动|
| upper-threshold| Number|50|距顶部/左边多远时（单位px），触发 scrolltoupper 事件|
| ower-threshold |Number| 50| 距底部/右边多远时（单位px），触发 scrolltolower 事件|
| scroll-top | Number | |设置竖向滚动条位置|
| scroll-left | Number | |设置横向滚动条位置|
| scroll-into-view |String | |值应为某子元素id（id不能以数字开头）。设置哪个方向可滚动，则在哪个方向滚动到该元素|
| scroll-with-animation | Boolean | false| 在设置滚动条位置时使用动画过渡|
| enable-back-to-top | Boolean | false | iOS点击顶部状态栏、安卓双击标题栏时，滚动条返回顶部，只支持竖向|
| bindscrolltoupper | EventHandle | |滚动到顶部/左边，会触发 scrolltoupper 事件|
| bindscrolltolower | EventHandle | |滚动到底部/右边，会触发 scrolltolower 事件|
| bindscroll | EventHandle | | 滚动时触发，event.detail = {scrollLeft, scrollTop, scrollHeight, scrollWidth, deltaX, deltaY}|
>使用竖向滚动时，需要给<scroll-view/>一个固定高度，通过 WXSS 设置 height。
示例代码：
```
<view class="section">
<view class="section__title">vertical scroll</view>
<scroll-view scroll-y style="height: 200px;" bindscrolltoupper="upper" bindscrolltolower="lower" bindscroll="scroll" scroll-into-view="{{toView}}" scroll-top="{{scrollTop}}">
<view id="green" class="scroll-view-item bc_green"></view>
<view id="red" class="scroll-view-item bc_red"></view>
<view id="yellow" class="scroll-view-item bc_yellow"></view>
<view id="blue" class="scroll-view-item bc_blue"></view>
</scroll-view>
<view class="btn-area">
<button size="mini" bindtap="tap">click me to scroll into view </button>
<button size="mini" bindtap="tapMove">click me to scroll</button>
</view>
</view>
<view class="section section_gap">
<view class="section__title">horizontal scroll</view>
<scroll-view class="scroll-view_H" scroll-x style="width: 100%">
<view id="green" class="scroll-view-item_H bc_green"></view>
<view id="red" class="scroll-view-item_H bc_red"></view>
<view id="yellow" class="scroll-view-item_H bc_yellow"></view>
<view id="blue" class="scroll-view-item_H bc_blue"></view>
</scroll-view>
</view>
```
```
var order = ['red', 'yellow', 'blue', 'green', 'red']
Page({
data: {
toView: 'red',
scrollTop: 100
},
upper: function(e) {
console.log(e)
},
lower: function(e) {
console.log(e)
},
scroll: function(e) {
console.log(e)
},
tap: function(e) {
for (var i = 0; i < order.length; ++i) {
if (order[i] === this.data.toView) {
this.setData({
toView: order[i + 1]
})
break
}
}
},
tapMove: function(e) {
this.setData({
scrollTop: this.data.scrollTop + 10
})
}
})
```
>Bug & Tip
1. tip: 请勿在 scroll-view 中使用 textarea、map、canvas、video 组件
2. tip: scroll-into-view 的优先级高于 scroll-top
3. tip: 在滚动 scroll-view 时会阻止页面回弹，所以在 scroll-view 中滚动，是无法触发 onPullDownRefresh
4. tip: 若要使用下拉刷新，请使用页面的滚动，而不是 scroll-view ，这样也能通过点击顶部状态栏回到页面顶部
