fix($browser): prevent infinite digests when clearing the hash of a url

By using `location.hash` to update the current browser location when only
the hash has changed, we prevent the browser from attempting to reload.

Closes angular#9629
Closes angular#9635
Closes angular#10228

Author: petebacondarwin

src/ng/browser.js

@@ -61,6 +61,11 @@ function Browser(window, document, $log, $sniffer) {
     }
   }
 
+  function getHash(url) {
+    var index = url.indexOf('#');
+    return index === -1 ? '' : url.substr(index + 1);
+  }
+
   /**
    * @private
    * Note: this method is used only by scenario runner
@@ -190,8 +195,10 @@ function Browser(window, document, $log, $sniffer) {
         }
         if (replace) {
           location.replace(url);
-        } else {
+        } else if (!sameBase) {
           location.href = url;
+        } else {
+          location.hash = getHash(url);
         }
       }
       return self;

test/ng/browserSpecs.js

@@ -1,5 +1,7 @@
 'use strict';
 
+/* global getHash:true, stripHash:true */
+
 var historyEntriesLength;
 var sniffer = {};
 
@@ -51,6 +53,12 @@ function MockWindow(options) {
       mockWindow.history.state = null;
       historyEntriesLength++;
     },
+    get hash() {
+      return getHash(locationHref);
+    },
+    set hash(value) {
+      locationHref = stripHash(locationHref) + '#' + value;
+    },
     replace: function(url) {
       locationHref = url;
       mockWindow.history.state = null;
@@ -550,6 +558,17 @@ describe('browser', function() {
       expect(locationReplace).not.toHaveBeenCalled();
     });
 
+    it("should retain the # character when the only change is clearing the hash fragment, to prevent page reload", function() {
+      sniffer.history = true;
+
+      browser.url('http://server/#123');
+      expect(fakeWindow.location.href).toEqual('http://server/#123');
+
+      browser.url('http://server/');
+      expect(fakeWindow.location.href).toEqual('http://server/#');
+
+    });
+
     it('should use location.replace when history.replaceState not available', function() {
       sniffer.history = false;
       browser.url('http://new.org', true);
@@ -561,6 +580,7 @@ describe('browser', function() {
       expect(fakeWindow.location.href).toEqual('http://server/');
     });
 
+
     it('should use location.replace and not use replaceState when the url only changed in the hash fragment to please IE10/11', function() {
       sniffer.history = true;
       browser.url('http://server/#123', true);
@@ -572,6 +592,7 @@ describe('browser', function() {
       expect(fakeWindow.location.href).toEqual('http://server/');
     });
 
+
     it('should return $browser to allow chaining', function() {
       expect(browser.url('http://any.com')).toBe(browser);
     });