scroll up an infiniteLoader that has scrollToIndex set bounces back to scrollToIndex

repro steps:

• have an infiniteloader with a list (or grid or …) with scrollToIndex set to something like 10000 => the list shows starting at the corresponding line
• scroll back up
• after a few lines the list jumps back to 10000 (only a few lines for Firefox, a bit more for Chrome) => this is only triggered when fresh data is loaded.

some investigation:

It looks very similar to https://github.com/bvaughn/react-virtualized/issues/595:

recomputeGridSize is called by InfiniteLoader once its new rows load. This in turn sets the _recomputeScrollTopFlag flag to true.

_recomputeScrollTopFlag is set to true in recomputeGridSize as follow:

this._recomputeScrollTopFlag = scrollToRow >= 0 && rowIndex <= scrollToRow;

I’m suspecting that this code is only valid when scrolling down but not up. If this is correct, recomputeGridSize should use this.state.scrollDirectionVertical to compute _recomputeScrollTopFlag and the same issue likely applies to horizontal scrolling too.

[mengdage]

@wuweiweiwu Hi, it seems like people are too busy to fix this bug. I create https://github.com/bvaughn/react-virtualized/pull/1154 with fixed tests.

[gigatesseract]

A tiny workaround

I was facing the same issue. I had to render 9k rows in total with a seek functionality for a particular row of interest. After seeking, scrolling up caused no issues, whereas when scrolling down, it automatically jumped to the already seeked row. (I am passing a state parameter to scrollToIndex prop which I am changing so that might rerender the list, but I could not explain why the issue does not come when scrolling up)
I solved the problem by resetting the scrollToIndex once scroll is complete.

this.setState({scrolled_index: index  + 20},  //this centers the row for my use case.    
          () =>{    
            this.setState({scrolled_index: -1})    
          });

I am passing this.state.scrolled_index to the List component. I am currently working in a project with deadlines. Will get a plunker up and running as soon as possible. Will love to see a fix for this issue.