Normalize NPCG in a regex route's matches to empty strings for undefined

src/app/HISTORY.md

@@ -13,13 +13,16 @@ App Framework Change History
 ### Router
 
 * Fixed issue with trying to URL-decode matching path segments that are
-  `undefined`. Routes defined as Regexps (instead of strings) can contain an
+  `undefined`. Routes defined as regexps (instead of strings) can contain an
   arbitrary number of captures; when executing the regex during dispatching, its
   array of matches can contain `undefined` values. Router will now check that a
-  match is a truthy value before trying to URL-decode it.
+  match is a truthy value before trying to URL-decode it, and coerce `undefined`
+  values to empty strings. ([#964][], [#1076][])
 
 
+[#964]: https://github.com/yui/yui3/issues/964
 [#1004]: https://github.com/yui/yui3/issues/1004
+[#1076]: https://github.com/yui/yui3/issues/1076
 
 
 3.11.0

src/app/js/router.js

@@ -670,7 +670,12 @@ Y.Router = Y.extend(Router, Y.Base, {
                 // Decode each of the path matches so that the any URL-encoded
                 // path segments are decoded in the `req.params` object.
                 matches = YArray.map(route.regex.exec(path) || [], function (match) {
-                    return match && decode(match);
+                    // Decode matches, or coerce `undefined` matches to an empty
+                    // string to match expectations of working with `req.params`
+                    // in the content of route dispatching, and normalize
+                    // browser differences in their handling of regexp NPCGs:
+                    // https://github.com/yui/yui3/issues/1076
+                    return (match && decode(match)) || '';
                 });
 
                 // Use named keys for parameter names if the route path contains

src/app/tests/unit/assets/router-test.js

@@ -993,14 +993,14 @@ routerSuite.add(new Y.Test.Case({
             calls += 1;
 
             Assert.isArray(req.params);
-            ArrayAssert.itemsAreSame(['/fnord/quux', 'fnord', 'fnord', undefined, 'quux'], req.params);
+            ArrayAssert.itemsAreSame(['/fnord/quux', 'fnord', 'fnord', '', 'quux'], req.params);
         });
 
         router.route(/^\/((blorp)|(blerf))\/(quux)$/, function (req) {
             calls += 1;
 
             Assert.isArray(req.params);
-            ArrayAssert.itemsAreSame(['/blerf/quux', 'blerf', undefined, 'blerf', 'quux'], req.params);
+            ArrayAssert.itemsAreSame(['/blerf/quux', 'blerf', '', 'blerf', 'quux'], req.params);
         });
 
         router._dispatch('/foo/one/two', {});