From 4cde844ffe6e2e129fab778a24ad5273dabcb59c Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Fri, 12 Oct 2018 15:25:38 +0200
Subject: [PATCH 1/2] Add a `DOMTokenList.toggle` polyfill for the second,
 optional, "force" parameter

This is based on the polyfill available at https://developer.mozilla.org/en-US/docs/Web/API/Element/classList#Polyfill
---
 src/shared/compatibility.js | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/shared/compatibility.js b/src/shared/compatibility.js
index d1417421b38e4..66eff05915037 100644
--- a/src/shared/compatibility.js
+++ b/src/shared/compatibility.js
@@ -90,6 +90,28 @@ const hasDOM = typeof window === 'object' && typeof document === 'object';
   };
 })();
 
+// Provides support for DOMTokenList.prototype.toggle, with the optional
+// "force" parameter, in legacy browsers.
+// Support: IE
+(function checkDOMTokenListToggle() {
+  if (!hasDOM || isNodeJS()) {
+    return;
+  }
+  const div = document.createElement('div');
+  if (div.classList.toggle('test', 0) === false) {
+    return;
+  }
+  const originalDOMTokenListToggle = DOMTokenList.prototype.toggle;
+
+  DOMTokenList.prototype.toggle = function(token) {
+    if (arguments.length > 1) {
+      const force = !!arguments[1];
+      return (this[force ? 'add' : 'remove'](token), force);
+    }
+    return originalDOMTokenListToggle(token);
+  };
+})();
+
 // Provides support for String.prototype.includes in legacy browsers.
 // Support: IE, Chrome<41
 (function checkStringIncludes() {

From ea4db64f417dde6a2d4ec576d5bbbe2160684a04 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Fri, 12 Oct 2018 15:29:45 +0200
Subject: [PATCH 2/2] Convert some occurrences, in the `/web` folder, of
 `classList.{add, remove}` to `classList.toggle` with the "force" parameter

---
 web/base_viewer.js       | 14 ++++----------
 web/pdf_find_bar.js      |  8 ++------
 web/secondary_toolbar.js |  8 ++++----
 web/toolbar.js           |  6 +-----
 4 files changed, 11 insertions(+), 25 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index bf8f091a85fe4..d97ff24a25a40 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -1038,16 +1038,10 @@ class BaseViewer {
   _updateScrollMode(pageNumber = null) {
     const scrollMode = this._scrollMode, viewer = this.viewer;
 
-    if (scrollMode === ScrollMode.HORIZONTAL) {
-      viewer.classList.add('scrollHorizontal');
-    } else {
-      viewer.classList.remove('scrollHorizontal');
-    }
-    if (scrollMode === ScrollMode.WRAPPED) {
-      viewer.classList.add('scrollWrapped');
-    } else {
-      viewer.classList.remove('scrollWrapped');
-    }
+    viewer.classList.toggle('scrollHorizontal',
+                            scrollMode === ScrollMode.HORIZONTAL);
+    viewer.classList.toggle('scrollWrapped',
+                            scrollMode === ScrollMode.WRAPPED);
 
     if (!this.pdfDocument || !pageNumber) {
       return;
diff --git a/web/pdf_find_bar.js b/web/pdf_find_bar.js
index e3becbd67cd99..665352797a607 100644
--- a/web/pdf_find_bar.js
+++ b/web/pdf_find_bar.js
@@ -132,13 +132,9 @@ class PDFFindBar {
         break;
     }
 
-    if (notFound) {
-      this.findField.classList.add('notFound');
-    } else {
-      this.findField.classList.remove('notFound');
-    }
-
+    this.findField.classList.toggle('notFound', notFound);
     this.findField.setAttribute('data-status', status);
+
     Promise.resolve(findMsg).then((msg) => {
       this.findMsg.textContent = msg;
       this._adjustWidth();
diff --git a/web/secondary_toolbar.js b/web/secondary_toolbar.js
index bb41f2068cb2f..b9f6f6701d9fd 100644
--- a/web/secondary_toolbar.js
+++ b/web/secondary_toolbar.js
@@ -123,11 +123,11 @@ class SecondaryToolbar {
     // current `BaseViewer` instance (in particular `PDFSinglePageViewer`).
     this.eventBus.on('baseviewerinit', (evt) => {
       if (evt.source instanceof PDFSinglePageViewer) {
-        this.toolbarButtonContainer.classList.add('hiddenScrollModeButtons');
-        this.toolbarButtonContainer.classList.add('hiddenSpreadModeButtons');
+        this.toolbarButtonContainer.classList.add('hiddenScrollModeButtons',
+                                                  'hiddenSpreadModeButtons');
       } else {
-        this.toolbarButtonContainer.classList.remove('hiddenScrollModeButtons');
-        this.toolbarButtonContainer.classList.remove('hiddenSpreadModeButtons');
+        this.toolbarButtonContainer.classList.remove('hiddenScrollModeButtons',
+                                                     'hiddenSpreadModeButtons');
       }
     });
   }
diff --git a/web/toolbar.js b/web/toolbar.js
index 622b5dd20d17e..997284fc25051 100644
--- a/web/toolbar.js
+++ b/web/toolbar.js
@@ -224,11 +224,7 @@ class Toolbar {
   updateLoadingIndicatorState(loading = false) {
     let pageNumberInput = this.items.pageNumber;
 
-    if (loading) {
-      pageNumberInput.classList.add(PAGE_NUMBER_LOADING_INDICATOR);
-    } else {
-      pageNumberInput.classList.remove(PAGE_NUMBER_LOADING_INDICATOR);
-    }
+    pageNumberInput.classList.toggle(PAGE_NUMBER_LOADING_INDICATOR, loading);
   }
 
   _adjustScaleWidth() {