From 0f67b470261fb7b1a1650fbd80e75ba218d8503f Mon Sep 17 00:00:00 2001
From: Sudheer <sudheer.105@gmail.com>
Date: Fri, 20 Sep 2019 00:09:52 +0530
Subject: [PATCH] Revert "Call scrollToIndex only when ref is set and index is
 in range (#3282)" (#3284)

This reverts commit ecbbb3f0e5c1a48fe793009a243c1e4f5510fafe.
---
 app/components/post_list/post_list.js      | 31 ++++++++++------------
 app/components/post_list/post_list.test.js | 26 ------------------
 2 files changed, 14 insertions(+), 43 deletions(-)

diff --git a/app/components/post_list/post_list.js b/app/components/post_list/post_list.js
index 588e8ae8c..d55b77126 100644
--- a/app/components/post_list/post_list.js
+++ b/app/components/post_list/post_list.js
@@ -299,33 +299,30 @@ export default class PostList extends PureComponent {
 
     scrollToBottom = () => {
         setTimeout(() => {
-            if (this.flatListRef?.current) {
+            if (this.flatListRef && this.flatListRef.current) {
                 this.flatListRef.current.scrollToOffset({offset: 0, animated: true});
             }
         }, 250);
     };
 
-    flatListScrollToIndex = (index) => {
-        this.flatListRef.current.scrollToIndex({
-            animated: false,
-            index,
-            viewOffset: 0,
-            viewPosition: 1, // 0 is at bottom
-        });
-    }
-
     scrollToIndex = (index) => {
-        this.animationFrameInitialIndex = requestAnimationFrame(() => {
-            if (this.flatListRef?.current && index > 0 && index <= this.getItemCount()) {
-                this.flatListScrollToIndex(index);
-            }
-        });
+        if (this.flatListRef?.current) {
+            this.animationFrameInitialIndex = requestAnimationFrame(() => {
+                this.flatListRef.current.scrollToIndex({
+                    animated: false,
+                    index,
+                    viewOffset: 0,
+                    viewPosition: 1, // 0 is at bottom
+                });
+            });
+        }
     };
 
     scrollToInitialIndexIfNeeded = (index, count = 0) => {
-        if (!this.hasDoneInitialScroll) {
+        if (!this.hasDoneInitialScroll && this.flatListRef?.current) {
+            this.hasDoneInitialScroll = true;
+
             if (index > 0 && index <= this.getItemCount()) {
-                this.hasDoneInitialScroll = true;
                 this.scrollToIndex(index);
             } else if (count < 3) {
                 setTimeout(() => {
diff --git a/app/components/post_list/post_list.test.js b/app/components/post_list/post_list.test.js
index ffcf4e76b..a4219bf89 100644
--- a/app/components/post_list/post_list.test.js
+++ b/app/components/post_list/post_list.test.js
@@ -55,30 +55,4 @@ describe('PostList', () => {
         expect(baseProps.actions.handleSelectChannelByName).toHaveBeenCalled();
         expect(wrapper.getElement()).toMatchSnapshot();
     });
-
-    test('should call flatListScrollToIndex only when ref is set and index is in range', () => {
-        jest.spyOn(global, 'requestAnimationFrame').mockImplementation((cb) => cb());
-
-        const instance = wrapper.instance();
-        const flatListScrollToIndex = jest.spyOn(instance, 'flatListScrollToIndex');
-        const indexInRange = baseProps.postIds.length;
-        const indexOutOfRange = [-1, indexInRange + 1];
-
-        instance.flatListRef = {};
-        instance.scrollToIndex(indexInRange);
-        expect(flatListScrollToIndex).not.toHaveBeenCalled();
-
-        instance.flatListRef = {
-            current: {
-                scrollToIndex: jest.fn(),
-            },
-        };
-        for (const index of indexOutOfRange) {
-            instance.scrollToIndex(index);
-            expect(flatListScrollToIndex).not.toHaveBeenCalled();
-        }
-
-        instance.scrollToIndex(indexInRange);
-        expect(flatListScrollToIndex).toHaveBeenCalled();
-    });
 });