feat(modal): trap focus in modal for tabbing

- Trap focus inside modal when tabbing while modal is in focus

Closes #3689
Closes #4004
Fixes #738

Author: paulorbpacheco

src/modal/docs/demo.html

@@ -6,7 +6,7 @@ <h3 class="modal-title">I'm a modal!</h3>
         <div class="modal-body">
             <ul>
                 <li ng-repeat="item in items">
-                    <a ng-click="selected.item = item">{{ item }}</a>
+                    <a href="#" ng-click="$event.preventDefault(); selected.item = item">{{ item }}</a>
                 </li>
             </ul>
             Selected: <b>{{ selected.item }}</b>

src/modal/modal.js

@@ -196,6 +196,13 @@ angular.module('ui.bootstrap.modal', [])
         NOW_CLOSING_EVENT: 'modal.stack.now-closing'
       };
 
+      //Modal focus behavior
+      var focusableElementList;
+      var focusIndex = 0;
+      var tababbleSelector = 'a[href], area[href], input:not([disabled]), ' +
+        'button:not([disabled]),select:not([disabled]), textarea:not([disabled]), ' +
+        'iframe, object, embed, *[tabindex], *[contenteditable=true]';
+
       function backdropIndex() {
         var topBackdropIndex = -1;
         var opened = openedWindows.keys();
@@ -207,7 +214,7 @@ angular.module('ui.bootstrap.modal', [])
         return topBackdropIndex;
       }
 
-      $rootScope.$watch(backdropIndex, function(newBackdropIndex){
+      $rootScope.$watch(backdropIndex, function(newBackdropIndex) {
         if (backdropScope) {
           backdropScope.index = newBackdropIndex;
         }
@@ -281,15 +288,35 @@ angular.module('ui.bootstrap.modal', [])
       }
 
       $document.bind('keydown', function (evt) {
-        var modal;
+        var modal = openedWindows.top();
+        if (modal && modal.value.keyboard) {
+          switch (evt.which){
+            case 27: {
+              evt.preventDefault();
+              $rootScope.$apply(function () {
+                $modalStack.dismiss(modal.key, 'escape key press');
+              });
+              break;
+            }
+            case 9: {
+              $modalStack.loadFocusElementList(modal);
+              var focusChanged = false;
+              if (evt.shiftKey) {
+                if ($modalStack.isFocusInFirstItem(evt)) {
+                  focusChanged = $modalStack.focusLastFocusableElement();
+                }
+              } else {
+                if ($modalStack.isFocusInLastItem(evt)) {
+                  focusChanged = $modalStack.focusFirstFocusableElement();
+                }
+              }
 
-        if (evt.which === 27) {
-          modal = openedWindows.top();
-          if (modal && modal.value.keyboard) {
-            evt.preventDefault();
-            $rootScope.$apply(function () {
-              $modalStack.dismiss(modal.key, 'escape key press');
-            });
+              if (focusChanged) {
+                evt.preventDefault();
+                evt.stopPropagation();
+              }
+              break;
+            }
           }
         }
       });
@@ -338,6 +365,7 @@ angular.module('ui.bootstrap.modal', [])
         openedWindows.top().value.modalOpener = modalOpener;
         body.append(modalDomEl);
         body.addClass(OPENED_MODAL_CLASS);
+        $modalStack.clearFocusListCache();
       };
 
       function broadcastClosing(modalWindow, resultOrReason, closing) {
@@ -382,6 +410,51 @@ angular.module('ui.bootstrap.modal', [])
         }
       };
 
+      $modalStack.focusFirstFocusableElement = function() {
+        if (focusableElementList.length > 0) {
+          focusableElementList[0].focus();
+          return true;
+        }
+        return false;
+      };
+      $modalStack.focusLastFocusableElement = function() {
+        if (focusableElementList.length > 0) {
+          focusableElementList[focusableElementList.length - 1].focus();
+          return true;
+        }
+        return false;
+      };
+
+      $modalStack.isFocusInFirstItem = function(evt) {
+        if (focusableElementList.length > 0) {
+          return (evt.target || evt.srcElement) == focusableElementList[0];
+        }
+        return false;
+      };
+
+      $modalStack.isFocusInLastItem = function(evt) {
+        if (focusableElementList.length > 0) {
+          return (evt.target || evt.srcElement) == focusableElementList[focusableElementList.length - 1];
+        }
+        return false;
+      };
+
+      $modalStack.clearFocusListCache = function() {
+        focusableElementList = [];
+        focusIndex = 0;
+      };
+
+      $modalStack.loadFocusElementList = function(modalWindow) {
+        if (focusableElementList === undefined || !focusableElementList.length0) {
+          if (modalWindow) {
+            var modalDomE1 = modalWindow.value.modalDomEl;
+            if (modalDomE1 && modalDomE1.length) {
+              focusableElementList = modalDomE1[0].querySelectorAll(tababbleSelector);
+            }
+          }
+        }
+      };
+
       return $modalStack;
     }])
 

src/modal/test/modal.spec.js

@@ -2,9 +2,11 @@ describe('$modal', function () {
   var $animate, $controllerProvider, $rootScope, $document, $compile, $templateCache, $timeout, $q;
   var $modal, $modalProvider;
 
-  var triggerKeyDown = function (element, keyCode) {
+  var triggerKeyDown = function (element, keyCode, shiftKey) {
     var e = $.Event('keydown');
+    e.srcElement = element[0];
     e.which = keyCode;
+    e.shiftKey = shiftKey;
     element.trigger(e);
   };
 
@@ -344,6 +346,40 @@ describe('$modal', function () {
       openAndCloseModalWithAutofocusElement();
       openAndCloseModalWithAutofocusElement();
     });
+
+    it('should change focus to first element when tab key was pressed', function() {
+      var initialPage = angular.element('<a href="#" id="cannot-get-focus-from-modal">Outland link</a>');
+      angular.element(document.body).append(initialPage);
+      initialPage.focus();
+
+      open({
+        template:'<a href="#" id="tab-focus-link"><input type="text" id="tab-focus-input1"/><input type="text" id="tab-focus-input2"/>' +
+        '<button id="tab-focus-button">Open me!</button>'
+      });
+      expect($document).toHaveModalsOpen(1);
+
+      var lastElement = angular.element(document.getElementById('tab-focus-button'));
+      lastElement.focus();
+      triggerKeyDown(lastElement, 9);
+      expect(document.activeElement.getAttribute('id')).toBe('tab-focus-link');
+    });
+
+    it('should change focus to last element when shift+tab key is pressed', function() {
+      var initialPage = angular.element('<a href="#" id="cannot-get-focus-from-modal">Outland link</a>');
+      angular.element(document.body).append(initialPage);
+      initialPage.focus();
+
+      open({
+        template:'<a href="#" id="tab-focus-link"><input type="text" id="tab-focus-input1"/><input type="text" id="tab-focus-input2"/>' +
+        '<button id="tab-focus-button">Open me!</button>'
+      });
+      expect($document).toHaveModalsOpen(1);
+
+      var lastElement = angular.element(document.getElementById('tab-focus-link'));
+      lastElement.focus();
+      triggerKeyDown(lastElement, 9, true);
+      expect(document.activeElement.getAttribute('id')).toBe('tab-focus-button');
+    });
   });
 
   describe('default options can be changed in a provider', function () {