Handle the pathological case described in whatwg/urlpattern#210.

.eleventy.js

@@ -35,6 +35,9 @@ module.exports = function(eleventyConfig, options = {}) {
     // In the unlikely event it has a special URL pattern character, escape it.
     let root = eleventyConfig.getFilter("url")("/", eleventyConfig.pathPrefix);
     let escapedRoot = root.replaceAll(/[{}()*?+:]/g, "\\$&");
+    if (/[:?#]/.test(escapedRoot)) {
+        escapedRoot = `{${escapedRoot.slice(0, -1)}}/`;
+    }
     let condition = {href_matches: escapedRoot + "*"};
     if (exclude.length !== 0) {
         let excludePatterns = exclude.map(e => e.replace(/^\/(?!\/)/, escapedRoot));

test/Test.js

@@ -69,6 +69,20 @@ test("with a path prefix and exclusions", async t => {
     t.snapshot(index.content);
 });
 
+test("with a path prefix with stronger escaping needs", async t => {
+    // This path prefix not only contains :, a special character, but that
+    // character also needs to be further escaped to avoid being treated as a
+    // scheme separator.
+    // https://github.com/whatwg/urlpattern/issues/210
+    let eleventy = makeEleventy({
+        pathPrefix: "/zone:5/",
+        pluginOptions: {exclude: ["/dynamic/*"]},
+    });
+    let json = await eleventy.toJSON();
+    let index = json.find(p => p.url === '/');
+    t.snapshot(index.content);
+});
+
 test("with prerender", async t => {
     let eleventy = makeEleventy({
         pluginOptions: {action: "prerender"}

test/snapshots/Test.js.md

@@ -32,6 +32,13 @@ Generated by [AVA](https://avajs.dev).
     `<script type="speculationrules">{"prefetch":[{"source":"document","where":{"and":[{"href_matches":"/foo/bar/*"},{"not":{"href_matches":["/foo/bar/admin/*","/foo/bar/logout"]}}]},"eagerness":"moderate"}]}</script>␊
     `
 
+## with a path prefix with stronger escaping needs
+
+> Snapshot 1
+
+    `<script type="speculationrules">{"prefetch":[{"source":"document","where":{"and":[{"href_matches":"{/zone\\\\:5}/*"},{"not":{"href_matches":["{/zone\\\\:5}/dynamic/*"]}}]},"eagerness":"moderate"}]}</script>␊
+    `
+
 ## with prerender
 
 > Snapshot 1