Changeset 41876 for trunk/src/wp-admin/js/theme-plugin-editor.js

Timestamp:

10/16/2017 05:58:07 PM (7 years ago)

Author:

afercia

Message:

Accessibility: Improve the File Editors interstitial warning.

The warning displayed upon first visit on the File Editors introduced in [41774]
needs to be the only perceivable content in the page for users of assistive
technologies. It looks like a modal but it's not exactly an ARIA dialog, not an
ARIA alert either, and needs some special treatment.

• constrains tabbing within the modal
• uses wp.a11y.speak() to make screen readers announce the modal message
• hides all the other page content from assistive technologies using aria-hidden="true"

This way, even if users miss the speak message, the warning is actually the only
perceivable content in the page.

Fixes #42110.

File:

• trunk/src/wp-admin/js/theme-plugin-editor.js (modified) (3 diffs)

trunk/src/wp-admin/js/theme-plugin-editor.js

@@ -52 +52 @@
 
         if ( component.warning.length > 0 ) {
-            $( 'body' ).addClass( 'modal-open' );
-            component.warning.find( '.file-editor-warning-go-back' ).focus();
-            component.warning.on( 'click', '.file-editor-warning-dismiss', component.dismissWarning );
+            component.showWarning();
         }
 
@@ -79 +77 @@
 
     /**
+     * Set up and display the warning modal.
+     *
+     * @since 4.9.0
+     * @returns {void}
+     */
+    component.showWarning = function() {
+        // Get the text within the modal.
+        var rawMessage = component.warning.find( '.file-editor-warning-message' ).text();
+        // Hide all the #wpwrap content from assistive technologies.
+        $( '#wpwrap' ).attr( 'aria-hidden', 'true' );
+        // Detach the warning modal from its position and append it to the body.
+        $( document.body )
+            .addClass( 'modal-open' )
+            .append( component.warning.detach() );
+        // Reveal the modal and set focus on the go back button.
+        component.warning
+            .removeClass( 'hidden' )
+            .find( '.file-editor-warning-go-back' ).focus();
+        // Get the links and buttons within the modal.
+        component.warningTabbables = component.warning.find( 'a, button' );
+        // Attach event handlers.
+        component.warningTabbables.on( 'keydown', component.constrainTabbing );
+        component.warning.on( 'click', '.file-editor-warning-dismiss', component.dismissWarning );
+        // Make screen readers announce the warning message after a short delay (necessary for some screen readers).
+        setTimeout( function() {
+            wp.a11y.speak( wp.sanitize.stripTags( rawMessage.replace( /\s+/g, ' ' ) ), 'assertive' );
+        }, 1000 );
+    };
+
+    /**
+     * Constrain tabbing within the warning modal.
+     *
+     * @since 4.9.0
+     * @param {object} event jQuery event object.
+     * @returns {void}
+     */
+    component.constrainTabbing = function( event ) {
+        var firstTabbable, lastTabbable;
+
+        if ( 9 !== event.which ) {
+            return;
+        }
+
+        firstTabbable = component.warningTabbables.first()[0];
+        lastTabbable = component.warningTabbables.last()[0];
+
+        if ( lastTabbable === event.target && ! event.shiftKey ) {
+            firstTabbable.focus();
+            event.preventDefault();
+        } else if ( firstTabbable === event.target && event.shiftKey ) {
+            lastTabbable.focus();
+            event.preventDefault();
+        }
+    };
+
+    /**
      * Dismiss the warning modal.
      *
@@ -92 +146 @@
         // Hide modal.
         component.warning.remove();
+        $( '#wpwrap' ).removeAttr( 'aria-hidden' );
         $( 'body' ).removeClass( 'modal-open' );
-
-        // Return focus - is this a trap?
-        component.instance.codemirror.focus();
     };