点击添加按钮，新添加的元素保持在底部小demo的实现

WXML代码:

1. <!--index.wxml-->
2. <button type="primary" bindtap="addItemFn">添加</button>
3. <scroll-view class="scroll" scroll-y="true" scroll-top="{{scrollTop}}" >
4. <view class="classname"></view>
5. <block wx:for="{{lists}}" wx:key="*this">
6. <view class="item" data-index="{{index}}" id="item{{index}}">item {{index}}--{{item.place}}</view>
7. </block>
8. </scroll-view>

WXSS代码：

1. page{height: 100%;}
2. .scroll{height:400rpx; border: 2px solid #f00;}
3. .item{ background: #ddd; margin: 10px 0; height: 40px;}

JS代码：

1. //获取应用实例
2. var app = getApp()
3. Page({
4. data: {
5. lists: [
6. { place: "北京" },
7. { place: "深圳" },
8. { place: "上海" },
9. { place: "广州" },
10. { place: "珠海" }
11. ],
12. //记录item个数
13. itemCount: 5,
14. scrollTop: 100,//设置滚动条到顶部的距离
15.  
16. },
17. //事件处理函数
18. addItemFn: function () {
19. var {lists, itemCount} = this.data;
20. var newData = { place: "default" };
21. lists.push(newData);
22. this.setData({
23. lists: lists,
24. itemCount: itemCount,
25. })

1. //单独拿出来用setData 放一个里会出现问题
2.  
3. this.setData({
4. scrollTop: this.data.scrollTop + 50 // 50代表你要添加的元素的高度