From 27ccb6363d6965fd7f3d3791ae8ef4d4e016e793 Mon Sep 17 00:00:00 2001
From: Alex Tran <hello@alextran.org>
Date: Sun, 27 Oct 2019 23:49:10 -0500
Subject: [PATCH 1/2] Include skip link JS for IE.

---
 assets/js/skip-link-focus-fix.js | 33 ++++++++++++++++++++++++++++++++
 functions.php                    |  1 +
 2 files changed, 34 insertions(+)
 create mode 100644 assets/js/skip-link-focus-fix.js

diff --git a/assets/js/skip-link-focus-fix.js b/assets/js/skip-link-focus-fix.js
new file mode 100644
index 000000000..2325149cd
--- /dev/null
+++ b/assets/js/skip-link-focus-fix.js
@@ -0,0 +1,33 @@
+/**
+ * File skip-link-focus-fix.js.
+ *
+ * Helps with accessibility for keyboard only users.
+ *
+ * This is the source file for what is minified in the twentynineteen_skip_link_focus_fix() PHP function.
+ *
+ * Learn more: https://git.io/vWdr2
+ */
+( function() {
+	var isIe = /(trident|msie)/i.test( navigator.userAgent );
+
+	if ( isIe && document.getElementById && window.addEventListener ) {
+		window.addEventListener( 'hashchange', function() {
+			var id = location.hash.substring( 1 ),
+				element;
+
+			if ( ! ( /^[A-z0-9_-]+$/.test( id ) ) ) {
+				return;
+			}
+
+			element = document.getElementById( id );
+
+			if ( element ) {
+				if ( ! ( /^(?:a|select|input|button|textarea)$/i.test( element.tagName ) ) ) {
+					element.tabIndex = -1;
+				}
+
+				element.focus();
+			}
+		}, false );
+	}
+}() );
diff --git a/functions.php b/functions.php
index 6e87c7656..d71400a4c 100644
--- a/functions.php
+++ b/functions.php
@@ -200,6 +200,7 @@ function twentytwenty_register_scripts() {
 	}
 
 	wp_enqueue_script( 'twentytwenty-js', get_template_directory_uri() . '/assets/js/index.js', array(), $theme_version, false );
+	wp_enqueue_script( 'skip-link-focus-fix', get_template_directory_uri() . '/assets/js/skip-link-focus-fix.js', array(), $theme_version, true );
 	wp_script_add_data( 'twentytwenty-js', 'async', true );
 
 }

From 7c841da97a08b4f10bf5685d92ded64585824e05 Mon Sep 17 00:00:00 2001
From: Alex Tran <hello@alextran.org>
Date: Mon, 28 Oct 2019 03:07:08 -0500
Subject: [PATCH 2/2] Output minified script without enqueuing it

---
 assets/js/skip-link-focus-fix.js |  2 +-
 functions.php                    | 19 ++++++++++++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/assets/js/skip-link-focus-fix.js b/assets/js/skip-link-focus-fix.js
index 2325149cd..181b79799 100644
--- a/assets/js/skip-link-focus-fix.js
+++ b/assets/js/skip-link-focus-fix.js
@@ -3,7 +3,7 @@
  *
  * Helps with accessibility for keyboard only users.
  *
- * This is the source file for what is minified in the twentynineteen_skip_link_focus_fix() PHP function.
+ * This is the source file for what is minified in the twentytwenty_skip_link_focus_fix() PHP function.
  *
  * Learn more: https://git.io/vWdr2
  */
diff --git a/functions.php b/functions.php
index d71400a4c..925db5477 100644
--- a/functions.php
+++ b/functions.php
@@ -200,13 +200,30 @@ function twentytwenty_register_scripts() {
 	}
 
 	wp_enqueue_script( 'twentytwenty-js', get_template_directory_uri() . '/assets/js/index.js', array(), $theme_version, false );
-	wp_enqueue_script( 'skip-link-focus-fix', get_template_directory_uri() . '/assets/js/skip-link-focus-fix.js', array(), $theme_version, true );
 	wp_script_add_data( 'twentytwenty-js', 'async', true );
 
 }
 
 add_action( 'wp_enqueue_scripts', 'twentytwenty_register_scripts' );
 
+/**
+ * Fix skip link focus in IE11.
+ *
+ * This does not enqueue the script because it is tiny and because it is only for IE11,
+ * thus it does not warrant having an entire dedicated blocking script being loaded.
+ *
+ * @link https://git.io/vWdr2
+ */
+function twentytwenty_skip_link_focus_fix() {
+	// The following is minified via `terser --compress --mangle -- assets/js/skip-link-focus-fix.js`.
+	?>
+	<script>
+	/(trident|msie)/i.test(navigator.userAgent)&&document.getElementById&&window.addEventListener&&window.addEventListener("hashchange",function(){var t,e=location.hash.substring(1);/^[A-z0-9_-]+$/.test(e)&&(t=document.getElementById(e))&&(/^(?:a|select|input|button|textarea)$/i.test(t.tagName)||(t.tabIndex=-1),t.focus())},!1);
+	</script>
+	<?php
+}
+add_action( 'wp_print_footer_scripts', 'twentytwenty_skip_link_focus_fix' );
+
 /**
  * Register navigation menus uses wp_nav_menu in five places.
  */