From 0b841bf268134a9caa5d75c9843bdad24a364109 Mon Sep 17 00:00:00 2001
From: Sean Yesmunt <sean@lbry.io>
Date: Mon, 22 Jul 2019 19:43:30 -0400
Subject: [PATCH] add scroll selector

---
 src/ui/component/router/index.js | 5 ++---
 src/ui/component/router/view.jsx | 2 +-
 src/ui/redux/reducers/app.js     | 2 ++
 src/ui/redux/selectors/app.js    | 5 +++++
 4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/ui/component/router/index.js b/src/ui/component/router/index.js
index 699e590ba..11f9ee843 100644
--- a/src/ui/component/router/index.js
+++ b/src/ui/component/router/index.js
@@ -1,10 +1,9 @@
 import { connect } from 'react-redux';
+import { selectScrollStartingPosition } from 'redux/selectors/app';
 import Router from './view';
 
 const select = state => ({
-  scroll: state.app.scrollHistory[state.app.scrollHistory.length - 1],
-  scrollHistory: state.app.scrollHistory,
-  currentScroll: state.app.currentScroll || 0,
+  currentScroll: selectScrollStartingPosition(state),
 });
 
 export default connect(select)(Router);
diff --git a/src/ui/component/router/view.jsx b/src/ui/component/router/view.jsx
index 90be7b36c..13f6b3872 100644
--- a/src/ui/component/router/view.jsx
+++ b/src/ui/component/router/view.jsx
@@ -22,7 +22,7 @@ import NavigationHistory from 'page/navigationHistory';
 import TagsPage from 'page/tags';
 import FollowingPage from 'page/following';
 
-// Let app handle scroll
+// Tell the browser we are handling scroll restoration
 if ('scrollRestoration' in history) {
   history.scrollRestoration = 'manual';
 }
diff --git a/src/ui/redux/reducers/app.js b/src/ui/redux/reducers/app.js
index cc32dcc02..bea508dcf 100644
--- a/src/ui/redux/reducers/app.js
+++ b/src/ui/redux/reducers/app.js
@@ -67,6 +67,8 @@ const defaultState: AppState = {
   scrollHistory: [0],
 };
 
+// @@router comes from react-router
+// This action is dispatched any time a user navigates forward or back
 reducers['@@router/LOCATION_CHANGE'] = (state, action) => {
   const { currentScroll } = state;
   const scrollHistory = state.scrollHistory.slice();
diff --git a/src/ui/redux/selectors/app.js b/src/ui/redux/selectors/app.js
index 276c0496f..7ddd1ae03 100644
--- a/src/ui/redux/selectors/app.js
+++ b/src/ui/redux/selectors/app.js
@@ -123,3 +123,8 @@ export const selectSearchOptionsExpanded = createSelector(
   selectState,
   state => state.searchOptionsExpanded
 );
+
+export const selectScrollStartingPosition = createSelector(
+  selectState,
+  state => state.currentScroll
+);