Fix skip link 404 error on refresh bug

Problem:
When a user uses the skip link anchor to skip the navigation, the
route was being changed to /#main-content. This route does not
exist. If a user were to manually refresh the page, it would
return a 404. This link is critical to meet accessibility
guidelines and is needed by users that navigate with a keyboard.

The challenge is that we need to mirror a full page refresh on all
route changes, so we set focus on the app-header element on each route
change. When we click the skip to navigation link, there should not be
a route change. All we need is to set focus on the <main> element so
that the user can tab to the first tabbable element in the main content
section.

Solution:
- Use a native <a> element with an attached click event handler
- Prevent the default action of adding the hash to the URL
- Create a global mixin to reuse for route changes and skip link
activation
- Emit an event that can be listened for to call the global mixin

Signed-off-by: Derick Montague <derick.montague@ibm.com>
Change-Id: I4c2301b02f608eeb376ed2d1bd809f3d5c1bf545

5 files changed, 37 insertions, 16 deletions

diff --git a/src/components/AppHeader/AppHeader.vue b/src/components/AppHeader/AppHeader.vue
index 7e1a1006..0e8d3db4 100644
--- a/src/components/AppHeader/AppHeader.vue
+++ b/src/components/AppHeader/AppHeader.vue
@@ -1,7 +1,11 @@
 <template>
   <div>
     <header id="page-header">
-      <a role="link" class="link-skip-nav btn btn-light" href="#main-content">
+      <a
+        class="link-skip-nav btn btn-light"
+        href="#main-content"
+        @click="setFocus"
+      >
         {{ $t('appHeader.skipToContent') }}
       </a>
 
@@ -207,6 +211,10 @@ export default {
     toggleNavigation() {
       this.$root.$emit('toggle-navigation');
     },
+    setFocus(event) {
+      event.preventDefault();
+      this.$root.$emit('skip-navigation');
+    },
   },
 };
 </script>
diff --git a/src/components/Global/PageContainer.vue b/src/components/Global/PageContainer.vue
index e766d38d..c979759b 100644
--- a/src/components/Global/PageContainer.vue
+++ b/src/components/Global/PageContainer.vue
@@ -5,11 +5,17 @@
 </template>
 
 <script>
+import SetFocusMixin from '@/components/Mixins/SetFocusMixin';
 export default {
   name: 'PageContainer',
+  mixins: [SetFocusMixin],
+  created() {
+    this.$root.$on('skip-navigation', () => {
+      this.setFocus(this.$el);
+    });
+  },
 };
 </script>
-
 <style lang="scss" scoped>
 main {
   width: 100%;
@@ -18,6 +24,12 @@ main {
   padding-bottom: $spacer * 3;
   padding-left: $spacer;
   padding-right: $spacer;
+
+  &:focus-visible {
+    box-shadow: inset 0 0 0 2px theme-color('primary');
+    outline: none;
+  }
+
   @include media-breakpoint-up($responsive-layout-bp) {
     padding-left: $spacer * 2;
   }
diff --git a/src/components/Mixins/SetFocusMixin.js b/src/components/Mixins/SetFocusMixin.js
new file mode 100644
index 00000000..ae3e8e0f
--- /dev/null
+++ b/src/components/Mixins/SetFocusMixin.js
@@ -0,0 +1,12 @@
+const setFocusMixin = {
+  methods: {
+    setFocus(element) {
+      element.setAttribute('tabindex', '-1');
+      element.focus();
+      // Reason: https://axesslab.com/skip-links/#update-3-a-comment-from-gov-uk
+      element.removeAttribute('tabindex');
+    },
+  },
+};
+
+export default setFocusMixin;
diff --git a/src/layouts/AppLayout.vue b/src/layouts/AppLayout.vue
index c2023dfb..d5b4c3df 100644
--- a/src/layouts/AppLayout.vue
+++ b/src/layouts/AppLayout.vue
@@ -15,6 +15,7 @@ import AppHeader from '@/components/AppHeader';
 import AppNavigation from '@/components/AppNavigation';
 import PageContainer from '@/components/Global/PageContainer';
 import ButtonBackToTop from '@/components/Global/ButtonBackToTop';
+import SetFocusMixin from '@/components/Mixins/SetFocusMixin';
 
 export default {
   name: 'App',
@@ -24,6 +25,7 @@ export default {
     PageContainer,
     ButtonBackToTop,
   },
+  mixins: [SetFocusMixin],
   data() {
     return {
       routerKey: 0,
@@ -31,20 +33,8 @@ export default {
   },
   watch: {
     $route: function () {
-      // $nextTick = DOM updated
       this.$nextTick(function () {
-        // Get the focusTarget DOM element
-        let focusTarget = this.$refs.focusTarget.$el;
-
-        // Make focustarget programmatically focussable
-        focusTarget.setAttribute('tabindex', '-1');
-
-        // Focus element
-        focusTarget.focus();
-
-        // Remove tabindex from focustarget
-        // Reason: https://axesslab.com/skip-links/#update-3-a-comment-from-gov-uk
-        focusTarget.removeAttribute('tabindex');
+        this.setFocus(this.$refs.focusTarget.$el);
       });
     },
   },
diff --git a/tests/unit/__snapshots__/AppHeader.spec.js.snap b/tests/unit/__snapshots__/AppHeader.spec.js.snap
index 3e5c91eb..02d99b16 100644
--- a/tests/unit/__snapshots__/AppHeader.spec.js.snap
+++ b/tests/unit/__snapshots__/AppHeader.spec.js.snap
@@ -8,7 +8,6 @@ exports[`AppHeader.vue should render correctly 1`] = `
     <a
       class="link-skip-nav btn btn-light"
       href="#main-content"
-      role="link"
     >
       
       appHeader.skipToContent