infinite scroll: make sure more data is always loaded if scrolled to top/bottom quickly

Author: Leah Bentley

src/features/infinite-scroll/js/infinite-scroll.js

@@ -289,6 +289,15 @@
  }
 
  if (args.y) {
+ if (args.y.percentage === 0 || args.y.percentage === 1) {
+ // User has scrolled all the way to the top/bottom.
+ // If the user is scrolling very quickly all the way to the top/bottom, the scroll handler can get confused
+ // about the direction. This ensures that more data always is loaded in this case.
+ args.grid.scrollDirection = args.y.percentage === 0 ? uiGridConstants.scrollDirection.UP : uiGridConstants.scrollDirection.DOWN;
+ service.loadData(args.grid);
+ return;
+ }
+
  var percentage;
  var targetPercentage = args.grid.options.infiniteScrollRowsFromEnd / args.grid.renderContainers.body.visibleRowCache.length;
  if (args.grid.scrollDirection === uiGridConstants.scrollDirection.UP ) {