fix(infinitescroll): make sure more data is always loaded if scrolled to top/bottom quickly (#5183)

Author: Leah Bentley

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

@@ -289,17 +289,28 @@
  }
 
  if (args.y) {
- var percentage;
- var targetPercentage = args.grid.options.infiniteScrollRowsFromEnd / args.grid.renderContainers.body.visibleRowCache.length;
- if (args.grid.scrollDirection === uiGridConstants.scrollDirection.UP ) {
- percentage = args.y.percentage;
- if (percentage <= targetPercentage){
- service.loadData(args.grid);
- }
- } else if (args.grid.scrollDirection === uiGridConstants.scrollDirection.DOWN) {
- percentage = 1 - args.y.percentage;
- if (percentage <= targetPercentage){
- service.loadData(args.grid);
+
+ // If the user is scrolling very quickly all the way to the top/bottom, the scroll handler can get confused
+ // about the direction. First we check if they've gone all the way, and data always is loaded in this case.
+ if (args.y.percentage === 0) {
+ args.grid.scrollDirection = uiGridConstants.scrollDirection.UP;
+ service.loadData(args.grid);
+ } else if (args.y.percentage === 1) {
+ args.grid.scrollDirection = uiGridConstants.scrollDirection.DOWN;
+ service.loadData(args.grid);
+ } else { // Scroll position is somewhere in between top/bottom, so determine whether it's far enough to load more data.
+ var percentage;
+ var targetPercentage = args.grid.options.infiniteScrollRowsFromEnd / args.grid.renderContainers.body.visibleRowCache.length;
+ if (args.grid.scrollDirection === uiGridConstants.scrollDirection.UP ) {
+ percentage = args.y.percentage;
+ if (percentage <= targetPercentage){
+ service.loadData(args.grid);
+ }
+ } else if (args.grid.scrollDirection === uiGridConstants.scrollDirection.DOWN) {
+ percentage = 1 - args.y.percentage;
+ if (percentage <= targetPercentage){
+ service.loadData(args.grid);
+ }
  }
  }
  }