From 8f7435f3fc99881cd9ff911531408c9e2c03304a Mon Sep 17 00:00:00 2001
From: David Sevilla Martin <me@datitisev.me>
Date: Fri, 20 Mar 2020 09:58:33 -0400
Subject: [PATCH] forum: fix post stream scrubber dragging on mobile

---
 js/src/forum/components/PostStreamScrubber.tsx | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/js/src/forum/components/PostStreamScrubber.tsx b/js/src/forum/components/PostStreamScrubber.tsx
index aa9e48315..6f120ceac 100644
--- a/js/src/forum/components/PostStreamScrubber.tsx
+++ b/js/src/forum/components/PostStreamScrubber.tsx
@@ -373,22 +373,24 @@ export default class PostStreamScrubber extends Component {
         );
     }
 
-    onmousedown(e) {
-        this.mouseStart = e.clientY || e.originalEvent.touches[0].clientY;
+    onmousedown(e: MouseEvent) {
+        this.mouseStart = window.TouchEvent && e instanceof TouchEvent ? e.touches[0].clientY : e.clientY;
         this.indexStart = this.index;
         this.dragging = true;
         this.stream.paused = true;
         $('body').css('cursor', 'move');
     }
 
-    onmousemove(e) {
+    onmousemove(e: MouseEvent) {
         if (!this.dragging) return;
 
+        let y = window.TouchEvent && e instanceof TouchEvent ? e.touches[0].clientY : e.clientY;
+
         // Work out how much the mouse has moved by - first in pixels, then
         // convert it to a percentage of the scrollbar's height, and then
         // finally convert it into an index. Add this delta index onto
         // the index at which the drag was started, and then scroll there.
-        const deltaPixels = (e.clientY || e.originalEvent.touches[0].clientY) - this.mouseStart;
+        const deltaPixels = y - this.mouseStart;
         const deltaPercent = (deltaPixels / this.$('.Scrubber-scrollbar').outerHeight()) * 100;
         const deltaIndex = deltaPercent / this.percentPerPost().index || 0;
         const newIndex = Math.min(this.indexStart + deltaIndex, this.count() - 1);