From a30d12312a2e6949147e6e3c866c53420a4288df Mon Sep 17 00:00:00 2001
From: Xaver Maierhofer <xaver.maierhofer@xwissen.info>
Date: Tue, 26 Dec 2017 18:14:23 +0100
Subject: [PATCH] [BUGFIX] Support CustomEvent in IE

---
 lib/sidebar.js |  2 +-
 polyfill.js    | 20 +++++++++++++++++++-
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/lib/sidebar.js b/lib/sidebar.js
index c042c88..b28cf3c 100644
--- a/lib/sidebar.js
+++ b/lib/sidebar.js
@@ -15,7 +15,7 @@ define(function () {
     el.appendChild(sidebar);
 
     var button = document.createElement('button');
-    var visibility = new Event('visibility');
+    var visibility = new CustomEvent('visibility');
     sidebar.appendChild(button);
 
     button.classList.add('sidebarhandle');
diff --git a/polyfill.js b/polyfill.js
index 856beb2..c646e44 100644
--- a/polyfill.js
+++ b/polyfill.js
@@ -8,7 +8,7 @@ if (!String.prototype.includes) {
 }
 
 if (typeof Object.assign !== 'function') {
-  Object.assign = function(target, varArgs) { // .length of function is 2
+  Object.assign = function (target, varArgs) { // .length of function is 2
     if (target == null) { // TypeError if undefined or null
       throw new TypeError('Cannot convert undefined or null to object');
     }
@@ -30,3 +30,21 @@ if (typeof Object.assign !== 'function') {
     return to;
   };
 }
+
+// eslint-disable-next-line consistent-return
+(function () {
+  if (typeof window.CustomEvent === 'function') {
+    return false;
+  }
+
+  function CustomEvent(event, params) {
+    params = params || { bubbles: false, cancelable: false, detail: undefined };
+    var evt = document.createEvent('CustomEvent');
+    evt.initCustomEvent(event, params.bubbles, params.cancelable, params.detail);
+    return evt;
+  }
+
+  CustomEvent.prototype = window.Event.prototype;
+
+  window.CustomEvent = CustomEvent;
+})();