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));