Parses a given URL breaking it out into its parts.

parseUrl.js

(function (RGX_PLUS, RGX_SLASH, RGX_PARAM, decodeURIComponent, undefined) {
  /**
   * @license Copyright 2014 - Chris West - MIT Licensed
   * 
   * Parses a given URL breaking it out into its parts.
   * @param  {string} opt_url
   *     Optional.  The URL to be parsed and broken out into its individual
   *     parts.  Defaults to the URL of the current page if not given.
   * @return {!Object}
   *     Object containing the `href`, `protocol`, `host`, `hostname`, `port`,
   *     `pathname`, `search`, and `hash` for the given URL.  In addition the
   *     `params` and `hashParams` are specified in this object.  The `params`
   *     is an object containing the URL parameters found in the `search`.  The
   *     `hashParams` is an object containing the URL parameters found in the
   *     `hash`.  Ordinarily the value of each of the parameters will translated
   *     as strings but in the event that the same parameter is found multiple
   *     times the value will be an array of strings.
   */
  parseUrl = function (opt_url) {
    var a = document.createElement('a');
    a.href = opt_url == undefined ? location.href : opt_url;
    return {
      protocol: a.protocol,
      hostname: a.hostname,
      host: a.host,
      port: a.port,
      href: a.href,
      // http://stackoverflow.com/questions/956233/javascript-pathname-ie-quirk
      pathname: a.pathname.replace(RGX_SLASH, '/$&'),
      search: a.search,
      hash: a.hash,
      params: parseParams(a, 'search'),
      hashParams: parseParams(a, 'hash')
    };
  };

  function parseParams(a, prop) {
    var params = {}, hasOwnProperty = params.hasOwnProperty;
    (a[prop] || '')
      .replace(RGX_PLUS, ' ')
      .replace(RGX_PARAM, function(m, key, value) {
        key = decodeURIComponent(key);
        value = value && decodeURIComponent(value);
        params[key] = hasOwnProperty.call(params, key)
          ? [].concat(params[key], value)  // NB: error without Array
          : value;
      });
    return params;
  }
})(
  /\+/g,
  /^[^\/]/,
  /[#?&]([^=&]*)(?:=([^&]*))?(?=&|$)/g,
  decodeURIComponent
);