Menus: Validate custom links and add accessible error messages.

Add URL validation in the admin navigation menu manager that matches the validation in the customizer when adding custom links. Improve accessibility of both custom link forms by adding `aria-invalid` and `aria-describedby` attributes with visible error messages and announcing the error using `wp.a11y.speak()`.

Props joedolson, nikitasolanki1812, akrocks, pathan-amaankhan, rcreators, ironprogrammer, audrasjb, ankit-k-gupta, chaion07, rinkalpagdar, snehapatil02, jainil07, parthvataliya.
Fixes #60619, #60969.

git-svn-id: https://develop.svn.wordpress.org/trunk@59948 602fd350-edb4-49c9-b593-d223f7449a82

src/js/_enqueues/lib/nav-menu.js

@@ -1102,13 +1102,53 @@
 			}, 500 ) );
 
 			$('#add-custom-links input[type="text"]').on( 'keypress', function(e){
-				$('#customlinkdiv').removeClass('form-invalid');
+				$( '#customlinkdiv' ).removeClass( 'form-invalid' );
+				$( '#custom-menu-item-url' ).removeAttr( 'aria-invalid' ).removeAttr( 'aria-describedby' );
+				$( '#custom-url-error' ).hide();
 
 				if ( e.keyCode === 13 ) {
 					e.preventDefault();
 					$( '#submit-customlinkdiv' ).trigger( 'click' );
 				}
 			});
+
+			$( '#submit-customlinkdiv' ).on( 'click', function (e) {
+				var urlInput = $( '#custom-menu-item-url' ),
+					url = urlInput.val().trim(),
+					errorMessage = $( '#custom-url-error' ),
+					urlWrap = $( '#menu-item-url-wrap' ),
+					urlRegex;
+
+				// Hide the error message initially
+				errorMessage.hide();
+				urlWrap.removeClass( 'has-error' );
+
+				/*
+				 * Allow URLs including:
+				 * - http://example.com/
+				 * - //example.com
+				 * - /directory/
+				 * - ?query-param
+				 * - #target
+				 * - mailto:foo@example.com
+				 *
+				 * Any further validation will be handled on the server when the setting is attempted to be saved,
+				 * so this pattern does not need to be complete.
+				 */
+				urlRegex = /^((\w+:)?\/\/\w.*|\w+:(?!\/\/$)|\/|\?|#)/;
+				if ( ! urlRegex.test( url ) ) {
+					e.preventDefault();
+					urlInput.addClass( 'form-invalid' )
+						.attr( 'aria-invalid', 'true' )
+						.attr( 'aria-describedby', 'custom-url-error' );
+
+					errorMessage.show();
+					var errorText = errorMessage.text();
+					urlWrap.addClass( 'has-error' );
+					// Announce error message via screen reader
+					wp.a11y.speak( errorText, 'assertive' );
+				}
+			});
 		},
 
 		/**
@@ -1389,7 +1429,8 @@
 
 		addCustomLink : function( processMethod ) {
 			var url = $('#custom-menu-item-url').val().toString(),
-				label = $('#custom-menu-item-name').val();
+				label = $('#custom-menu-item-name').val(),
+				urlRegex;
 
 			if ( '' !== url ) {
 				url = url.trim();
@@ -1397,7 +1438,20 @@
 
 			processMethod = processMethod || api.addMenuItemToBottom;
 
-			if ( '' === url || 'https://' == url || 'http://' == url ) {
+			/*
+			 * Allow URLs including:
+			 * - http://example.com/
+			 * - //example.com
+			 * - /directory/
+			 * - ?query-param
+			 * - #target
+			 * - mailto:foo@example.com
+			 *
+			 * Any further validation will be handled on the server when the setting is attempted to be saved,
+			 * so this pattern does not need to be complete.
+			 */
+			urlRegex = /^((\w+:)?\/\/\w.*|\w+:(?!\/\/$)|\/|\?|#)/;
+			if ( ! urlRegex.test( url ) ) {
 				$('#customlinkdiv').addClass('form-invalid');
 				return false;
 			}

src/js/_enqueues/wp/customize/nav-menus.js

@@ -223,6 +223,9 @@
 
 			this.$el.on( 'input', '#custom-menu-item-name.invalid, #custom-menu-item-url.invalid', function() {
 				$( this ).removeClass( 'invalid' );
+				var errorMessageId = $( this ).attr( 'aria-describedby' );
+				$( '#' + errorMessageId ).hide();
+				$( this ).removeAttr( 'aria-invalid' ).removeAttr( 'aria-describedby' );
 			});
 
 			// Load available items if it looks like we'll need them.
@@ -546,8 +549,11 @@
 			var menuItem,
 				itemName = $( '#custom-menu-item-name' ),
 				itemUrl = $( '#custom-menu-item-url' ),
+				urlErrorMessage = $( '#custom-url-error' ),
+				nameErrorMessage = $( '#custom-name-error' ),
 				url = itemUrl.val().trim(),
-				urlRegex;
+				urlRegex,
+				errorText;
 
 			if ( ! this.currentMenuControl ) {
 				return;
@@ -566,15 +572,37 @@
 			 * so this pattern does not need to be complete.
 			 */
 			urlRegex = /^((\w+:)?\/\/\w.*|\w+:(?!\/\/$)|\/|\?|#)/;
-
-			if ( '' === itemName.val() ) {
-				itemName.addClass( 'invalid' );
-				return;
-			} else if ( ! urlRegex.test( url ) ) {
-				itemUrl.addClass( 'invalid' );
+			if ( ! urlRegex.test( url ) || '' === itemName.val() ) {
+				if ( ! urlRegex.test( url ) ) {
+					itemUrl.addClass( 'invalid' )
+						.attr( 'aria-invalid', 'true' )
+						.attr( 'aria-describedby', 'custom-url-error' );
+					urlErrorMessage.show();
+					errorText = urlErrorMessage.text();
+					// Announce error message via screen reader
+					wp.a11y.speak( errorText, 'assertive' );
+				}
+				if ( '' === itemName.val() ) {
+					itemName.addClass( 'invalid' )
+						.attr( 'aria-invalid', 'true' )
+						.attr( 'aria-describedby', 'custom-name-error' );
+					nameErrorMessage.show();
+					errorText = ( '' === errorText ) ? nameErrorMessage.text() : errorText + nameErrorMessage.text();
+					// Announce error message via screen reader
+					wp.a11y.speak( errorText, 'assertive' );
+				}
 				return;
 			}
 
+			urlErrorMessage.hide();
+			nameErrorMessage.hide();
+			itemName.removeClass( 'invalid' )
+				.removeAttr( 'aria-invalid', 'true' )
+				.removeAttr( 'aria-describedby', 'custom-name-error' );
+			itemUrl.removeClass( 'invalid' )
+				.removeAttr( 'aria-invalid', 'true' )
+				.removeAttr( 'aria-describedby', 'custom-name-error' );
+
 			menuItem = {
 				'title': itemName.val(),
 				'url': url,

src/wp-admin/css/nav-menus.css

@@ -377,11 +377,16 @@ input.bulk-select-switcher:focus + .bulk-select-button-label {
 
 /* Add Menu Item Boxes */
 .postbox .howto input,
-.customlinkdiv .menu-item-textbox {
+.customlinkdiv .menu-item-textbox,
+.customlinkdiv .error-message {
 	width: 180px;
 	float: right;
 }
 
+.customlinkdiv .error-message {
+	clear: right;
+}
+
 .accordion-container .outer-border {
 	margin: 0;
 }

src/wp-admin/includes/nav-menu.php

@@ -351,6 +351,7 @@ function wp_nav_menu_item_link_meta_box() {
 				type="text"<?php wp_nav_menu_disabled_check( $nav_menu_selected_id ); ?>
 				class="code menu-item-textbox form-required" placeholder="https://"
 			/>
+			<span id="custom-url-error" class="error-message" style="display: none;"><?php _e( 'Please provide a valid link.' ); ?></span>
 		</p>
 
 		<p id="menu-item-name-wrap" class="wp-clearfix">

src/wp-includes/class-wp-customize-nav-menus.php

@@ -1268,10 +1268,12 @@ final class WP_Customize_Nav_Menus {
 				<p id="menu-item-url-wrap" class="wp-clearfix">
 					<label class="howto" for="custom-menu-item-url"><?php _e( 'URL' ); ?></label>
 					<input id="custom-menu-item-url" name="menu-item[-1][menu-item-url]" type="text" class="code menu-item-textbox" placeholder="https://">
+					<span id="custom-url-error" class="error-message" style="display: none;"><?php _e( 'Please provide a valid link.' ); ?></span>
 				</p>
 				<p id="menu-item-name-wrap" class="wp-clearfix">
 					<label class="howto" for="custom-menu-item-name"><?php _e( 'Link Text' ); ?></label>
 					<input id="custom-menu-item-name" name="menu-item[-1][menu-item-title]" type="text" class="regular-text menu-item-textbox">
+					<span id="custom-name-error" class="error-message" style="display: none;"><?php _e( 'The link text cannot be empty.' ); ?></span>
 				</p>
 				<p class="button-controls">
 					<span class="add-to-menu">