From 60bb0928a8431455637e4d1e611f5d003060bcea Mon Sep 17 00:00:00 2001
From: Nolan Lawson <nolan@nolanlawson.com>
Date: Tue, 19 Sep 2017 08:00:29 -0700
Subject: [PATCH] Set touchstart listener to 'passive', remove 'once' (#5011)

---
 app/javascript/mastodon/is_mobile.js | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/app/javascript/mastodon/is_mobile.js b/app/javascript/mastodon/is_mobile.js
index e9903d59ef..dbdb30081d 100644
--- a/app/javascript/mastodon/is_mobile.js
+++ b/app/javascript/mastodon/is_mobile.js
@@ -1,3 +1,5 @@
+import detectPassiveEvents from 'detect-passive-events';
+
 const LAYOUT_BREAKPOINT = 1024;
 
 export function isMobile(width) {
@@ -5,11 +7,16 @@ export function isMobile(width) {
 };
 
 const iOS = /iPad|iPhone|iPod/.test(navigator.userAgent) && !window.MSStream;
+
 let userTouching = false;
+let listenerOptions = detectPassiveEvents.hasSupport ? { passive: true } : false;
 
-window.addEventListener('touchstart', () => {
+function touchListener() {
   userTouching = true;
-}, { once: true });
+  window.removeEventListener('touchstart', touchListener, listenerOptions);
+}
+
+window.addEventListener('touchstart', touchListener, listenerOptions);
 
 export function isUserTouching() {
   return userTouching;