From 257a4a516c551422ac4d2ae7cd879ac405a1a420 Mon Sep 17 00:00:00 2001
From: Erwin Mombay <erwinm@google.com>
Date: Sun, 25 Oct 2015 03:27:02 -0700
Subject: [PATCH] fix(history): fix url turning into /undefined in IE11/Edge

---
 src/history.js                  |  8 +++++++-
 test/functional/test-history.js | 16 ++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/history.js b/src/history.js
index 97c5dedaee8d..3683ab149dbd 100644
--- a/src/history.js
+++ b/src/history.js
@@ -282,7 +282,13 @@ export class HistoryBindingNatural_ {
       };
       replaceState = (state, opt_title, opt_url) => {
         this.unsupportedState_ = state;
-        this.origReplaceState_(state, opt_title, opt_url);
+        // NOTE: check for `undefined` since IE11 and Edge
+        // unexpectedly coerces it into a `string`.
+        if (opt_url !== undefined) {
+          this.origReplaceState_(state, opt_title, opt_url);
+        } else {
+          this.origReplaceState_(state, opt_title);
+        }
       };
     } else {
       pushState = (state, opt_title, opt_url) => {
diff --git a/test/functional/test-history.js b/test/functional/test-history.js
index f8fb97bcaf25..7e2cdfd99406 100644
--- a/test/functional/test-history.js
+++ b/test/functional/test-history.js
@@ -176,6 +176,22 @@ describe('HistoryBindingNatural', () => {
     expect(onStackIndexUpdated.callCount).to.equal(0);
   });
 
+  // This prevents IE11/Edge from coercing undefined to become the new url
+  it('should not pass in `url` argument to original replace state if ' +
+    'parameter is undefined', () => {
+    let argumentLength = 0;
+    let origReplace = window.history.replaceState;
+    window.history.replaceState = function() {
+      argumentLength = arguments.length;
+    };
+
+    let history2 = new HistoryBindingNatural_(window);
+
+    expect(argumentLength).to.equal(2);
+
+    window.history.replaceState = origReplace;
+  });
+
   it('should push new state in the window.history and notify', () => {
     return history.push().then((stackIndex) => {
       expect(history.stackIndex_).to.equal(stackIndex);