From 6dd9ad12db85fc163e78e15e8c0f62c27f5480a9 Mon Sep 17 00:00:00 2001
From: loynoir <loynoir@users.noreply.github.com>
Date: Sat, 7 Aug 2021 20:33:55 +0000
Subject: [PATCH] Add `useJsRegexpLookbehind` option (#105)

---
 index.d.ts |  7 +++++++
 index.js   | 24 +++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/index.d.ts b/index.d.ts
index b2ab84e..e69a967 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -242,6 +242,13 @@ export interface Options {
 	```
 	*/
 	readonly sortQueryParameters?: boolean;
+
+	/**
+	prefer js-regexp-lookbehind{@link https://caniuse.com/js-regexp-lookbehind}
+
+	@default true
+	*/
+	readonly preferJsRegexpLookbehind?: boolean;
 }
 
 /**
diff --git a/index.js b/index.js
index f8297f5..cd5c6d7 100644
--- a/index.js
+++ b/index.js
@@ -70,6 +70,8 @@ export default function normalizeUrl(urlString, options) {
 		removeSingleSlash: true,
 		removeDirectoryIndex: false,
 		sortQueryParameters: true,
+		// ref: https://caniuse.com/js-regexp-lookbehind
+		preferJsRegexpLookbehind: true,
 		...options,
 	};
 
@@ -121,7 +123,27 @@ export default function normalizeUrl(urlString, options) {
 
 	// Remove duplicate slashes if not preceded by a protocol
 	if (urlObject.pathname) {
-		urlObject.pathname = urlObject.pathname.replace(/(?<!\b[a-z][a-z\d+\-.]{1,50}:)\/{2,}/g, '/');
+		if (options.preferJsRegexpLookbehind) {
+			urlObject.pathname = urlObject.pathname.replace(
+				// prevent SyntaxError which can not be try-catch
+				new RegExp(
+					// generated from /(?<!\b[a-z][a-z\d+\-.]{1,50}:)\/{2,}/g
+					"/(?<!\\b[a-z][a-z\\d+\\-.]{1,50}:)\\/{2,}/g"
+				),
+				'/'
+			);
+		} else {
+			// ref: https://github.com/sindresorhus/normalize-url/blob/454970b662086e8856d1af074c7a57df96545b8b/index.js#L136
+			// TODO: Use the following instead when targeting Node.js 10
+			// `urlObj.pathname = urlObj.pathname.replace(/(?<!https?:)\/{2,}/g, '/');`
+			urlObject.pathname = urlObject.pathname.replace(/((?!:).|^)\/{2,}/g, (_, p1) => {
+				if (/^(?!\/)/g.test(p1)) {
+					return `${p1}/`;
+				}
+
+				return '/';
+			});
+		}
 	}
 
 	// Decode URI octets