[added] <Route ignoreScrollBehavior /> to opt out of scroll behavior for itself and descendants

modules/components/Route.js

@@ -53,7 +53,8 @@ var Route = React.createClass({
     handler: React.PropTypes.any.isRequired,
     getAsyncProps: React.PropTypes.func,
     path: React.PropTypes.string,
-    name: React.PropTypes.string
+    name: React.PropTypes.string,
+    ignoreScrollBehavior: React.PropTypes.bool
   },
 
   render: function () {

modules/components/Routes.js

@@ -163,6 +163,16 @@ function updateMatchComponents(matches, refs) {
   }
 }
 
+function shouldUpdateScroll(currentMatches, previousMatches) {
+  var commonMatches = currentMatches.filter(function (match) {
+    return previousMatches.indexOf(match) !== -1;
+  });
+
+  return !commonMatches.some(function (match) {
+    return match.route.props.ignoreScrollBehavior;
+  });
+}
+
 function returnNull() {
   return null;
 }
@@ -285,16 +295,19 @@ var Routes = React.createClass({
       } else if (abortReason) {
         this.goBack();
       } else {
-        this._handleStateChange = this.handleStateChange.bind(this, path, actionType);
+        this._handleStateChange = this.handleStateChange.bind(this, path, actionType, this.state.matches);
         this.setState(nextState);
       }
     });
   },
 
-  handleStateChange: function (path, actionType) {
-    updateMatchComponents(this.state.matches, this.refs);
+  handleStateChange: function (path, actionType, previousMatches) {
+    var currentMatches = this.state.matches;
+    updateMatchComponents(currentMatches, this.refs);
 
-    this.updateScroll(path, actionType);
+    if (shouldUpdateScroll(currentMatches, previousMatches)) {
+      this.updateScroll(path, actionType);
+    }
 
     if (this.props.onChange)
       this.props.onChange.call(this);

modules/components/__tests__/Routes-test.js

@@ -69,4 +69,93 @@ describe('A Routes', function () {
     });
   });
 
+  describe('that considers ignoreScrollBehavior when calling updateScroll', function () {
+    var component;
+    beforeEach(function () {
+      component = ReactTestUtils.renderIntoDocument(
+        Routes({ location: 'none' },
+          Route({ handler: NullHandler, ignoreScrollBehavior: true },
+            Route({ path: '/feed', handler: NullHandler }),
+            Route({ path: '/discover', handler: NullHandler })
+          ),
+          Route({ path: '/search', handler: NullHandler, ignoreScrollBehavior: true }),
+          Route({ path: '/about', handler: NullHandler })
+        )
+      );
+    });
+
+    function spyOnUpdateScroll(action) {
+      var didCall = false;
+
+      var realUpdateScroll = component.updateScroll;
+      component.updateScroll = function mockUpdateScroll() {
+        didCall = true;
+        realUpdateScroll.apply(component, arguments);
+      };
+
+      try {
+        action();
+      } finally {
+        component.updateScroll = realUpdateScroll;
+      }
+
+      return didCall;
+    }
+
+    afterEach(function () {
+      React.unmountComponentAtNode(component.getDOMNode());
+    });
+
+    it('calls updateScroll when no ancestors ignore scroll', function () {
+      component.updateLocation('/feed');
+
+      var calledUpdateScroll = spyOnUpdateScroll(function () {
+        component.updateLocation('/about');
+      });
+
+      expect(calledUpdateScroll).toEqual(true);
+    });
+
+    it('calls updateScroll when no ancestors ignore scroll even though source and target do', function () {
+      component.updateLocation('/feed');
+
+      var calledUpdateScroll = spyOnUpdateScroll(function () {
+        component.updateLocation('/search');
+      });
+
+      expect(calledUpdateScroll).toEqual(true);
+    });
+
+    it('calls updateScroll when source is same as target and does not ignore scroll', function () {
+      component.updateLocation('/about');
+
+      var calledUpdateScroll = spyOnUpdateScroll(function () {
+        component.updateLocation('/about?page=2');
+      });
+
+      expect(calledUpdateScroll).toEqual(true);
+    });
+
+    it('does not call updateScroll when common ancestor ignores scroll', function () {
+      component.updateLocation('/feed');
+
+      var calledUpdateScroll = spyOnUpdateScroll(function () {
+        component.updateLocation('/discover');
+      });
+
+      expect(calledUpdateScroll).toEqual(false);
+    });
+
+    it('does not call updateScroll when source is same as target and ignores scroll', function () {
+      component.updateLocation('/search');
+
+      var calledUpdateScroll = spyOnUpdateScroll(function () {
+        component.updateLocation('/search?q=test');
+      });
+
+      expect(calledUpdateScroll).toEqual(false);
+    });
+
+  });
+
 });