Issue 1841 - Replaced URI class with built-in URL objects

lib/url.js

Index: lib/url.js
===================================================================
new file mode 100644
--- /dev/null
+++ b/lib/url.js
@@ -0,0 +1,44 @@
+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-2015 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+window.URL = (function()
+{
+  let URL = window.URL || window.webkitURL;
+  let URLproperties = ["href", "protocol", "host", "hostname", "port", "pathname", "search"];

[Wladimir Palant, 2015/01/21 15:33:44]

Nit: This isn't proper camel case, should be URLProperties or UrlProperties (the
latter seems to be more in line with common guidelines but we don't do this
consistently).

[Sebastian Noack, 2015/01/21 17:48:18]

Done.

+
+  if (!URL || !URLproperties.every(prop => prop in new URL("")))

[Wladimir Palant, 2015/01/21 15:33:44]

This will create seven URL instances, seems unnecessarily wasteful.

[Sebastian Noack, 2015/01/21 15:58:04]

So what? This code runs only once, and an empty string should be fast to parse.
The alternative would be:

  let urlObj;
  if (!URL || (urlObj = new URL(""), !URLproperties.every(prop => prop in
urlObj)))
    ...

Or IMO even worse:

  function hasBuiltinURL()
  {
     if (!URL)
       return false;
     
     let urlObj = new URL("");
     return URLproperties.every(prop => prop in urlObj);
  }

  if (hasBuiltinURL())
    ...

I'd rather don't bloat the code just to save some negligible cycles during
initialization.

+  {
+    let doc = document.implementation.createHTMLDocument();
+
+    let base = doc.createElement("base");
+    doc.head.appendChild(base);

[Wladimir Palant, 2015/01/21 15:33:44]

I was about to suggest using xml:base (wouldn't require adding anything to a
document) but discovered that it's apparently deprecated, without any
replacement currently:
https://code.google.com/p/chromium/issues/detail?id=341854 :-(

+
+    let anchor = doc.createElement("a");
+    doc.body.appendChild(anchor);
+
+    URL = function(url, baseUrl)
+    {
+      base.href = baseUrl;

[Wladimir Palant, 2015/01/21 15:33:44]

This will stringify baseUrl, meaning typically assigning "undefined" which is
rather ugly. Maybe use baseUrl || "" here?

[Sebastian Noack, 2015/01/21 17:48:18]

Done.

+      anchor.href = url;
+
+      for (var prop of URLproperties)

[Wladimir Palant, 2015/01/21 15:33:44]

Nit: let prop?

[Sebastian Noack, 2015/01/21 17:48:18]

Done.

+        this[prop] = anchor[prop];
+    };
+  }
+
+  return URL;
+})();