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

lib/url.js

 /*
  * 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.

+  let URLProperties = ["href", "protocol", "host", "hostname", "port", "pathname", "search"];
 
-  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.

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

+      if (baseUrl instanceof URL)
+        base.href = baseUrl.href;
+      else
+        base.href = baseUrl || "";
       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.

+      for (let prop of URLProperties)
         this[prop] = anchor[prop];
     };
   }
 
   return URL;
 })();