Fix results and chat divs sometimes not scrolling due to large output

3 files changed, 22 insertions, 5 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 115a130..16a9213 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,12 @@
 # Changelog
 All notable changes to this project will be documented in this file.
 
+## [Unreleased]
+
+### Fixed
+- Results and chat areas sometimes didn't scroll to bottom when they should. This was caused by large result outputs
+  being larger than the scroll tolerance.
+
 ## [0.1.11.3] - 2021-06-22
 
 ### UI
diff --git a/app/javascript/channels/chat_room_channel.js b/app/javascript/channels/chat_room_channel.js
index af29953..514742f 100644
--- a/app/javascript/channels/chat_room_channel.js
+++ b/app/javascript/channels/chat_room_channel.js
@@ -10,14 +10,19 @@ consumer.subscriptions.create("ChatRoomChannel", {
   },
 
   received(data) {
+    // If scrolled to the bottom or near the bottom, then smooth scroll to the bottom.
+    var shouldScroll = false;
+    var chatOutputElement = document.getElementById("chat_output");
+    if ((chatOutputElement.scrollTop + 100) >= (chatOutputElement.scrollHeight - chatOutputElement.offsetHeight)) {
+      shouldScroll = true;
+    }
+
     // Called when there's incoming data on the websocket for this channel
     var node = document.createElement("P");
     node.innerHTML = data.html;
-    var chatOutputElement = document.getElementById("chat_output");
     chatOutputElement.appendChild(node);
 
-    // If scrolled to the bottom or near the bottom, then smooth scroll to the bottom.
-    if ((chatOutputElement.scrollTop + 100) >= (chatOutputElement.scrollHeight - chatOutputElement.offsetHeight)) {
+    if (shouldScroll) {
       chatOutputElement.scrollTo({
         top: chatOutputElement.scrollHeight, left: 0, behavior: 'smooth'
       });
diff --git a/app/views/game/finish_activity.js.erb b/app/views/game/finish_activity.js.erb
index fa3d228..f281986 100644
--- a/app/views/game/finish_activity.js.erb
+++ b/app/views/game/finish_activity.js.erb
@@ -4,10 +4,16 @@ var resultControlsDiv = document.getElementById("activity_controls");
 var outputHTML = "<%= j render(partial: "application/results", locals: { results: @results }) %>"
 
 if (resultOutputDiv) {
-  resultOutputDiv.innerHTML += outputHTML;
-
   // If scrolled to the bottom or near the bottom, then smooth scroll to the bottom.
+  //  (Check before adding output, because a large output could prevent the scroll when it shouldn't.)
+  var shouldScroll = false;
   if ((resultOutputDiv.scrollTop + 100) >= (resultOutputDiv.scrollHeight - resultOutputDiv.offsetHeight)) {
+    shouldScroll = true;
+  }
+
+  resultOutputDiv.innerHTML += outputHTML;
+
+  if (shouldScroll) {
     resultOutputDiv.scrollTo({
       top: resultOutputDiv.scrollHeight, left: 0, behavior: 'smooth'
     });