fix: bigData 更改数据源表格数据空白

dist/demo.css

@@ -162,6 +162,10 @@
   position: relative;
   line-height: 1.33;
   overflow: hidden; }
+  .u-table.copy .u-table-thead th {
+    -webkit-user-select: unset;
+    -ms-user-select: unset;
+    user-select: unset; }
   .u-table-body {
     position: relative; }
     .u-table-body .u-table-row-expand-columns-in-body .expand-icon-con {

src/lib/bigData.js

@@ -73,9 +73,12 @@ export default function bigData(Table) {
           _this.cachedRowParentIndex = [];
           _this.computeCachedRowParentIndex(newData);
           // fix：切换数据源，startIndex、endIndex错误
-          _this.currentIndex = 0;
-          _this.startIndex = _this.currentIndex; //数据开始位置
-          _this.endIndex = _this.currentIndex + _this.loadCount; 
+          if(_this.scrollTop <= 0) { // 增加scrollTop 判断，ncc场景下滚动条不在最上层， 会出现空白，因为重置了currentIndex没有重置滚动条
+            _this.currentIndex = 0;
+            _this.startIndex = _this.currentIndex; //数据开始位置
+            _this.endIndex = _this.currentIndex + _this.loadCount; 
+          }
+          
         }
         _this.treeData = [];
         _this.flatTreeData = [];