From 3c6deebd3a156d236cae434ba4e5345139d9d4ed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fredrik=20Adel=C3=B6w?= <freben@gmail.com>
Date: Wed, 11 Aug 2021 14:58:41 +0200
Subject: [PATCH 1/2] avoid use of negative lookbehind entirely
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Signed-off-by: Fredrik Adelöw <freben@gmail.com>
---
 index.js | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index f8297f5..616c961 100644
--- a/index.js
+++ b/index.js
@@ -120,8 +120,36 @@ export default function normalizeUrl(urlString, options) {
 	}
 
 	// Remove duplicate slashes if not preceded by a protocol
+	// NOTE: This could be implemented using a single negative lookbehind
+	// regex, but we avoid that to maintain compatibility with older js engines
+	// which do not have support for that feature.
 	if (urlObject.pathname) {
-		urlObject.pathname = urlObject.pathname.replace(/(?<!\b[a-z][a-z\d+\-.]{1,50}:)\/{2,}/g, '/');
+		// Split the string by occurrences of this protocol regex, and perform
+		// duplicate-slash replacement on the strings between those occurrences
+		// (if any).
+		const protocolRegex = /\b[a-z][a-z\d+\-.]{1,50}:\/\//g;
+
+		let lastIndex = 0;
+		let result = '';
+		for (;;) {
+			const match = protocolRegex.exec(urlObject.pathname);
+			if (!match) {
+				break;
+			}
+
+			const protocol = match[0];
+			const protocolAtIndex = match.index;
+			const intermediate = urlObject.pathname.slice(lastIndex, protocolAtIndex);
+
+			result += intermediate.replace(/\/{2,}/g, '/');
+			result += protocol;
+			lastIndex = protocolAtIndex + protocol.length;
+		}
+
+		const remnant = urlObject.pathname.slice(lastIndex, urlObject.pathname.length);
+		result += remnant.replace(/\/{2,}/g, '/');
+
+		urlObject.pathname = result;
 	}
 
 	// Decode URI octets

From 8c60278d750b98a66dade17da16cd7c3da788d69 Mon Sep 17 00:00:00 2001
From: Sindre Sorhus <sindresorhus@gmail.com>
Date: Wed, 11 Aug 2021 15:32:13 +0200
Subject: [PATCH 2/2] Update index.js

---
 index.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/index.js b/index.js
index 616c961..4727186 100644
--- a/index.js
+++ b/index.js
@@ -124,6 +124,8 @@ export default function normalizeUrl(urlString, options) {
 	// regex, but we avoid that to maintain compatibility with older js engines
 	// which do not have support for that feature.
 	if (urlObject.pathname) {
+		// TODO: Replace everything below with `urlObject.pathname = urlObject.pathname.replace(/(?<!\b[a-z][a-z\d+\-.]{1,50}:)\/{2,}/g, '/');` when Safari supports negative lookbehind.
+
 		// Split the string by occurrences of this protocol regex, and perform
 		// duplicate-slash replacement on the strings between those occurrences
 		// (if any).