From 878432784c35a27dd115ff888a2459df1344da69 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Mon, 11 Nov 2019 17:48:04 +0100
Subject: [PATCH] [PDFHistory] Move the IE11 `pushState`/`replaceState`
 work-around to `src/shared/compatibility.js` (PR 10461 follow-up)

I've always disliked the solution in PR 10461, since it required changes to the `PDFHistory` code itself to deal with a bug in IE11.
Now that IE11 support is limited, it seems reasonable to remove these `pushState`/`replaceState` hacks from the main code-base and simply use polyfills instead.
---
 src/shared/compatibility.js | 23 +++++++++++++++++++++++
 web/pdf_history.js          | 12 ++----------
 2 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/src/shared/compatibility.js b/src/shared/compatibility.js
index fafa9d7a40abe..2bc09b1cc49f5 100644
--- a/src/shared/compatibility.js
+++ b/src/shared/compatibility.js
@@ -25,6 +25,9 @@ globalScope._pdfjsCompatibilityChecked = true;
 const { isNodeJS, } = require('./is_node');
 
 const hasDOM = typeof window === 'object' && typeof document === 'object';
+const userAgent =
+  (typeof navigator !== 'undefined' && navigator.userAgent) || '';
+const isIE = /Trident/.test(userAgent);
 
 // Support: Node.js
 (function checkNodeBtoa() {
@@ -112,6 +115,26 @@ const hasDOM = typeof window === 'object' && typeof document === 'object';
   };
 })();
 
+// Provides support for window.history.{pushState, replaceState}, with the
+// `url` parameter set to `undefined`, without breaking the document URL.
+// Support: IE
+(function checkWindowHistoryPushStateReplaceState() {
+  if (!hasDOM || !isIE) {
+    return;
+  }
+  const OriginalPushState = window.history.pushState;
+  const OriginalReplaceState = window.history.replaceState;
+
+  window.history.pushState = function(state, title, url) {
+    const args = (url === undefined ? [state, title] : [state, title, url]);
+    OriginalPushState.apply(this, args);
+  };
+  window.history.replaceState = function(state, title, url) {
+    const args = (url === undefined ? [state, title] : [state, title, url]);
+    OriginalReplaceState.apply(this, args);
+  };
+})();
+
 // Provides support for String.prototype.startsWith in legacy browsers.
 // Support: IE, Chrome<41
 (function checkStringStartsWith() {
diff --git a/web/pdf_history.js b/web/pdf_history.js
index e8f29a83dd738..2e67e2758c299 100644
--- a/web/pdf_history.js
+++ b/web/pdf_history.js
@@ -306,18 +306,10 @@ class PDFHistory {
       }
     }
     if (shouldReplace) {
-      if (newUrl) {
-        window.history.replaceState(newState, '', newUrl);
-      } else {
-        window.history.replaceState(newState, '');
-      }
+      window.history.replaceState(newState, '', newUrl);
     } else {
       this._maxUid = this._uid;
-      if (newUrl) {
-        window.history.pushState(newState, '', newUrl);
-      } else {
-        window.history.pushState(newState, '');
-      }
+      window.history.pushState(newState, '', newUrl);
     }
 
     if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('CHROME') &&