From d9871d5f692a258e621c0766239c70a4c58d1f2a Mon Sep 17 00:00:00 2001
From: Dave Smith <getdavemail@gmail.com>
Date: Wed, 21 Sep 2022 19:01:56 +0100
Subject: [PATCH] href only if url is not empty

---
 .../block-library/src/navigation-submenu/index.php    | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/packages/block-library/src/navigation-submenu/index.php b/packages/block-library/src/navigation-submenu/index.php
index 3c41fb340cafb..6ff4899575b27 100644
--- a/packages/block-library/src/navigation-submenu/index.php
+++ b/packages/block-library/src/navigation-submenu/index.php
@@ -183,7 +183,16 @@ function render_block_core_navigation_submenu( $attributes, $content, $block ) {
 	if ( ! $open_on_click ) {
 		$item_url = isset( $attributes['url'] ) ? $attributes['url'] : '';
 		// Start appending HTML attributes to anchor tag.
-		$html .= '<a class="wp-block-navigation-item__content" href="' . esc_url( $item_url ) . '"';
+		$html .= '<a class="wp-block-navigation-item__content"';
+
+		// The href attribute on a and area elements is not required;
+		// when those elements do not have href attributes they do not create hyperlinks.
+		// But also The href attribute must have a value that is a valid URL potentially
+		// surrounded by spaces.
+		// see: https://html.spec.whatwg.org/multipage/links.html#links-created-by-a-and-area-elements.
+		if ( ! empty( $item_url ) ) {
+			$html .= ' href="' . esc_url( $item_url ) . '"';
+		}
 
 		if ( $is_active ) {
 			$html .= ' aria-current="page"';