From b34c7a0afeaf79a8bf5ce8382bffbcaef97e6fbc Mon Sep 17 00:00:00 2001
From: Zach Leatherman <zachleat@users.noreply.github.com>
Date: Tue, 10 Dec 2024 16:44:37 -0600
Subject: [PATCH] Fixes #3581

---
 src/Plugins/InputPathToUrl.js    | 31 ++++++++++++++++++++++---------
 test/InputPathToUrlPluginTest.js | 18 ++++++++++++++++++
 2 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/src/Plugins/InputPathToUrl.js b/src/Plugins/InputPathToUrl.js
index ddc60ed70..19c619400 100644
--- a/src/Plugins/InputPathToUrl.js
+++ b/src/Plugins/InputPathToUrl.js
@@ -45,6 +45,10 @@ function normalizeInputPath(targetInputPath, inputDir, sourceInputPath, contentM
 }
 
 function parseFilePath(filepath) {
+	if (filepath.startsWith("#") || filepath.startsWith("?")) {
+		return [filepath, ""];
+	}
+
 	try {
 		/* u: URL {
 			href: 'file:///tmpl.njk#anchor',
@@ -95,8 +99,15 @@ function FilterPlugin(eleventyConfig) {
 		let inputDir = eleventyConfig.directories.input;
 		let suffix = "";
 		[suffix, targetFilePath] = parseFilePath(targetFilePath);
-		// @ts-ignore
-		targetFilePath = normalizeInputPath(targetFilePath, inputDir, this.page.inputPath, contentMap);
+		if (targetFilePath) {
+			// @ts-ignore
+			targetFilePath = normalizeInputPath(
+				targetFilePath,
+				inputDir,
+				this.page.inputPath,
+				contentMap,
+			);
+		}
 
 		let urls = contentMap[targetFilePath];
 		if (!urls || urls.length === 0) {
@@ -134,13 +145,15 @@ function TransformPlugin(eleventyConfig, defaultOptions = {}) {
 
 		let suffix = "";
 		[suffix, targetFilepathOrUrl] = parseFilePath(targetFilepathOrUrl);
-		targetFilepathOrUrl = normalizeInputPath(
-			targetFilepathOrUrl,
-			inputDir,
-			// @ts-ignore
-			this.page.inputPath,
-			contentMap,
-		);
+		if (targetFilepathOrUrl) {
+			targetFilepathOrUrl = normalizeInputPath(
+				targetFilepathOrUrl,
+				inputDir,
+				// @ts-ignore
+				this.page.inputPath,
+				contentMap,
+			);
+		}
 
 		let urls = contentMap[targetFilepathOrUrl];
 		if (!targetFilepathOrUrl || !urls || urls.length === 0) {
diff --git a/test/InputPathToUrlPluginTest.js b/test/InputPathToUrlPluginTest.js
index 0dc665142..b42237910 100644
--- a/test/InputPathToUrlPluginTest.js
+++ b/test/InputPathToUrlPluginTest.js
@@ -172,3 +172,21 @@ test("Issue #3417 Using the transform with relative path (no dot slash)", async
     `<a href="/source/target/">Target</a>`
   );
 });
+
+test("Issue #3581 #build-cost-🧰", async (t) => {
+  let elev = new Eleventy("./test/stubs-virtual/", "./test/stubs-virtual/_site", {
+    configPath: false,
+    config: function (eleventyConfig) {
+      eleventyConfig.addPlugin(TransformPlugin);
+
+      eleventyConfig.addTemplate("source/test.njk", `<a href="#built-cost-🧰">Target</a>`)
+    },
+  });
+
+  let results = await elev.toJSON();
+
+  t.is(
+    getContentFor(results, "/source/test/index.html"),
+    `<a href="#built-cost-🧰">Target</a>`
+  );
+});