From b5a00fd77607cce83952c0e9c0969e506c41a310 Mon Sep 17 00:00:00 2001
From: Zach Leatherman <zachleat@users.noreply.github.com>
Date: Fri, 9 Aug 2024 15:48:14 -0500
Subject: [PATCH] Updates to heading-anchors for accessibility.

---
 content/blog/thirdpost.md    |  2 +-
 public/css/index.css         | 23 -------------
 public/js/heading-anchors.js | 64 ++++++++++++++++++++++++++++++++----
 3 files changed, 58 insertions(+), 31 deletions(-)

diff --git a/content/blog/thirdpost.md b/content/blog/thirdpost.md
index bdea878..7241473 100644
--- a/content/blog/thirdpost.md
+++ b/content/blog/thirdpost.md
@@ -25,7 +25,7 @@ function myCommand() {
 console.log('Test');
 ```
 
-### Unstyled
+### Heading with a [link](#code)
 
 Bring to the table win-win survival strategies to ensure proactive domination. At the end of the day, going forward, a new normal that has evolved from generation X is on the runway heading towards a streamlined cloud solution. User generated content in real-time will have multiple touchpoints for offshoring.
 
diff --git a/public/css/index.css b/public/css/index.css
index cd9d0bf..b75d493 100644
--- a/public/css/index.css
+++ b/public/css/index.css
@@ -256,26 +256,3 @@ header {
 	margin-right: 1em;
 }
 
-/* Direct Links / Headings */
-.heading-anchor {
-	text-decoration: none;
-	font-style: normal;
-	font-size: 1em;
-	margin-left: .25em;
-}
-a[href].heading-anchor,
-a[href].heading-anchor:visited {
-	color: transparent;
-}
-a[href].heading-anchor:focus,
-a[href].heading-anchor:hover {
-	text-decoration: underline;
-}
-a[href].heading-anchor:focus,
-:hover > a[href].heading-anchor {
-	color: #aaa;
-}
-
-h2 + .heading-anchor {
-	font-size: 1.5em;
-}
diff --git a/public/js/heading-anchors.js b/public/js/heading-anchors.js
index ea9d6cd..03134af 100644
--- a/public/js/heading-anchors.js
+++ b/public/js/heading-anchors.js
@@ -1,4 +1,5 @@
 // Thank you to https://github.com/daviddarnes/heading-anchors
+// Thank you to https://amberwilson.co.uk/blog/are-your-anchor-links-accessible/#what-are-anchor-links-exactly%3F
 
 class HeadingAnchors extends HTMLElement {
 	static register(tagName) {
@@ -7,22 +8,71 @@ class HeadingAnchors extends HTMLElement {
 		}
 	}
 
+	static defaultSelector = "h2,h3,h4";
+
+	static featureTest() {
+		return "replaceSync" in CSSStyleSheet.prototype;
+	}
+
+	static css = `
+.heading-anchor {
+	text-decoration: none;
+}
+/* For headings that already have links */
+:is(h1, h2, h3, h4, h5, h6):has(a[href]:not(.heading-anchor)):is(:hover, :focus-within) .heading-anchor:after {
+	content: "#";
+	content: "#" / "";
+}
+.heading-anchor:focus:after,
+.heading-anchor:hover:after {
+	content: "#";
+	content: "#" / "";
+}
+.heading-anchor:after {
+	margin-left: .25em;
+	color: #aaa;
+}`;
+
+	constructor() {
+		if (!HeadingAnchors.featureTest()) {
+			return;
+		}
+
+		super();
+
+		let sheet = new CSSStyleSheet();
+		sheet.replaceSync(HeadingAnchors.css);
+		document.adoptedStyleSheets = [...document.adoptedStyleSheets, sheet];
+	}
+
 	connectedCallback() {
+		if (!HeadingAnchors.featureTest()) {
+			return;
+		}
+
 		this.headings.forEach((heading) => {
-			if(!heading.querySelector("a.direct-link") || heading.hasAttribute("data-heading-anchors-optout")) {
-				heading.append(this.anchor(heading));
-				heading.setAttribute("tabindex", "-1");
+			if(!heading.hasAttribute("data-heading-anchors-optout")) {
+				let anchor = this.getAnchorElement(heading);
+				if(heading.querySelector(":scope a[href]")) {
+					// Fallback if the heading already has a link
+					anchor.setAttribute("aria-label", `Jump to section: ${heading.textContent}`);
+					heading.appendChild(anchor);
+				} else {
+					// entire heading is a link
+					for(let child of heading.childNodes) {
+						anchor.appendChild(child);
+					}
+					heading.appendChild(anchor);
+				}
 			}
 		});
 	}
 
-	anchor(heading) {
-		// TODO this would be good use case for shadow dom
+	getAnchorElement(heading) {
 		let anchor = document.createElement("a");
 		anchor.setAttribute("data-pagefind-ignore", "");
 		anchor.href = `#${heading.id}`;
 		anchor.classList.add("heading-anchor");
-		anchor.innerHTML = `<span class="visually-hidden">Jump to heading</span><span aria-hidden="true">#</span>`;
 		return anchor;
 	}
 
@@ -31,7 +81,7 @@ class HeadingAnchors extends HTMLElement {
 	}
 
 	get selector() {
-		return this.getAttribute("selector") || "h1,h2,h3,h4"
+		return this.getAttribute("selector") || HeadingAnchors.defaultSelector;
 	}
 }