parse URL + absolutize URL in javascript (URLUtils shim - http://url.spec.whatwg.org/#url)

URLUtils.js

/*jslint regexp: true, maxerr: 50, indent: 2 */
 
(function (global) {
  "use strict";
  
  function URLUtils(url, baseURL) {
    var m = String(url).replace(/^\s+|\s+$/g, "").match(/^([^:\/?#]+:)?(?:\/\/(?:([^:@\/?#]*)(?::([^:@\/?#]*))?@)?(([^:\/?#]*)(?::(\d*))?))?([^?#]*)(\?[^#]*)?(#[\s\S]*)?/);
    if (!m) {
      throw new RangeError();
    }
    var protocol = m[1] || "";
    var username = m[2] || "";
    var password = m[3] || "";
    var host = m[4] || "";
    var hostname = m[5] || "";
    var port = m[6] || "";
    var pathname = m[7] || "";
    var search = m[8] || "";
    var hash = m[9] || "";
    if (baseURL !== undefined) {
      var base = new URLUtils(baseURL);
      var flag = protocol === "" && host === "" && username === "";
      if (flag && pathname === "" && search === "") {
        search = base.search;
      }
      if (flag && pathname.charAt(0) !== "/") {
        pathname = (pathname !== "" ? (((base.host !== "" || base.username !== "") && base.pathname === "" ? "/" : "") + base.pathname.slice(0, base.pathname.lastIndexOf("/") + 1) + pathname) : base.pathname);
      }
      // dot segments removal
      var output = [];
      pathname.replace(/^(\.\.?(\/|$))+/, "")
        .replace(/\/(\.(\/|$))+/g, "/")
        .replace(/\/\.\.$/, "/../")
        .replace(/\/?[^\/]*/g, function (p) {
          if (p === "/..") {
            output.pop();
          } else {
            output.push(p);
          }
        });
      pathname = output.join("").replace(/^\//, pathname.charAt(0) === "/" ? "/" : "");
      if (flag) {
        port = base.port;
        hostname = base.hostname;
        host = base.host;
        password = base.password;
        username = base.username;
      }
      if (protocol === "") {
        protocol = base.protocol;
      }
    }
    this.origin = protocol + (protocol !== "" || host !== "" ? "//" : "") + host;
    this.href = protocol + (protocol !== "" || host !== "" ? "//" : "") + (username !== "" ? username + (password !== "" ? ":" + password : "") + "@" : "") + host + pathname + search + hash;
    this.protocol = protocol;
    this.username = username;
    this.password = password;
    this.host = host;
    this.hostname = hostname;
    this.port = port;
    this.pathname = pathname;
    this.search = search;
    this.hash = hash;
  }
 
  global.URLUtils = URLUtils;
 
}(this));

Great job. I'm going to give this a try.

Is this snippet in Public Domain? E.g. like Douglas Crockford's json.js and json2.js? Public domain is great no pressures to litter ones code with disclaimers.

of course

p.s.
all tests from here http://skew.org/uri/uri_tests.html passed

You're working too hard. :-) http://stackoverflow.com/a/12965135/1130377

(Unless you're using this in node or similar, where you wouldn't have an url resolver built into the browser DOM already, of course.)

@johan: I don't believe that works in IE, but even more so, crossing the DOM line from JavaScript tends to be slower than a native-JS solution. Requiring a DOM also prevent anyone from creating a cross-environment library.

Forked to fix a small bug: since pathname is guaranteed to start with /, adding an extra / before the leading part of base.pathname is unnecessary.

The following case breaks, as the @ gets detected as the auth part:

  https://service.domain.com/go?email=jim@jam.com

Suggested change is:

 var m = String(url).replace(/^\s+|\s+$/g, "").match(/^([^:\/?#]+:)?(?:\/\/(?:([^:@]*)(?::([^:@]*))?@)?(([^:\/?#]*)(?::(\d*))?))?([^?#]*)(\?[^#]*)?(#[\s\S]*)?/);

to

 var m = String(url).replace(/^\s+|\s+$/g, "").match(/^([^:\/?#]+:)?(?:\/\/(?:([^:@\/]*)(?::([^:@\/]*))?@)?(([^:\/?#]*)(?::(\d*))?))?([^?#]*)(\?[^#]*)?(#[\s\S]*)?/);

I'm not sure this is 100% correct though - better suggestions welcome.

@guybedford,
Thanks, good catch, I have updated my code.
the specification, written by Anne van Kesteren - https://url.spec.whatwg.org/#authority-state - tells, that "/", "", "?", and "#" should not be in "authority".

@Yaffle thanks so much for the quick response.

When updating to this new code in my tests, I've hit two more issues now unfortunately -

1. new URLUtils('asdf', 'http://example.org/test') gives an href of http://example.org//asdf instead of http://example.org/asdf
2. new URLUtils('asdf', 'file:///example.org/test') gives an href of file:/example.org/asdf instead of file:///example.org/asdf

These issues didn't happen in the original code that I'm still using though so will stick with that for now.

@guybedford, Thanks again,
I updated the code to fix those issues too. Possibly, there are other issues, I did not test well.
P.S. URLUtils tries to match URL API available in Chrome and Firefox - new URL('asdf', 'file:///example.org/test')

@Yaffle perhaps it is worth considering turning this into a polyfill repo?

@guybedford, there is one - https://github.com/Polymer/URL

A minor performance optimization for line 21 can be useful:

var base = baseURL instanceof URLUtils ? baseURL : new URLUtils(baseURL);