LibWeb: Factor out an 'initialize a URL' AO

This is a small refactor in the URL spec to avoid duplication as part of
the introduction of URL.parse, see:

https://github.com/whatwg/url/commit/58acb0

Userland/Libraries/LibWeb/DOMURL/DOMURL.cpp

@@ -2,6 +2,7 @@
  * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
  * Copyright (c) 2021, the SerenityOS developers.
  * Copyright (c) 2023, networkException <networkexception@serenityos.org>
+ * Copyright (c) 2024, Shannon Booth <shannon@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -50,6 +51,25 @@ static Optional<URL::URL> parse_api_url(String const& url, Optional<String> cons
     return parsed.is_valid() ? parsed : Optional<URL::URL> {};
 }
 
+// https://url.spec.whatwg.org/#url-initialize
+JS::NonnullGCPtr<DOMURL> DOMURL::initialize_a_url(JS::Realm& realm, URL::URL const& url_record)
+{
+    // 1. Let query be urlRecord’s query, if that is non-null; otherwise the empty string.
+    auto query = url_record.query().value_or(String {});
+
+    // 2. Set url’s URL to urlRecord.
+    // 3. Set url’s query object to a new URLSearchParams object.
+    auto query_object = MUST(URLSearchParams::construct_impl(realm, query));
+
+    // 4. Initialize url’s query object with query.
+    auto result_url = DOMURL::create(realm, url_record, move(query_object));
+
+    // 5. Set url’s query object’s URL object to url.
+    result_url->m_query->m_url = result_url;
+
+    return result_url;
+}
+
 // https://url.spec.whatwg.org/#dom-url-url
 WebIDL::ExceptionOr<JS::NonnullGCPtr<DOMURL>> DOMURL::construct_impl(JS::Realm& realm, String const& url, Optional<String> const& base)
 {
@@ -60,20 +80,8 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<DOMURL>> DOMURL::construct_impl(JS::Realm&
     if (!parsed_url.has_value())
         return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, "Invalid URL"sv };
 
-    // 3. Let query be parsedURL’s query, if that is non-null, and the empty string otherwise.
-    auto query = parsed_url->query().value_or(String {});
-
-    // 4. Set this’s URL to parsedURL.
-    // 5. Set this’s query object to a new URLSearchParams object.
-    auto query_object = MUST(URLSearchParams::construct_impl(realm, query));
-
-    // 6. Initialize this’s query object with query.
-    auto result_url = DOMURL::create(realm, parsed_url.release_value(), move(query_object));
-
-    // 7. Set this’s query object’s URL object to this.
-    result_url->m_query->m_url = result_url;
-
-    return result_url;
+    // 3. Initialize this with parsedURL.
+    return initialize_a_url(realm, parsed_url.value());
 }
 
 DOMURL::DOMURL(JS::Realm& realm, URL::URL url, JS::NonnullGCPtr<URLSearchParams> query)

Userland/Libraries/LibWeb/DOMURL/DOMURL.h

@@ -2,6 +2,7 @@
  * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
  * Copyright (c) 2021, the SerenityOS developers.
  * Copyright (c) 2023, networkException <networkexception@serenityos.org>
+ * Copyright (c) 2024, Shannon Booth <shannon@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -81,6 +82,8 @@ public:
 private:
     DOMURL(JS::Realm&, URL::URL, JS::NonnullGCPtr<URLSearchParams> query);
 
+    static JS::NonnullGCPtr<DOMURL> initialize_a_url(JS::Realm&, URL::URL const&);
+
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;