Cross-browser URL parsing in JavaScript

ParsedUrl.js

function ParsedUrl(url) {
	this.parse(url);
}

ParsedUrl.prototype.parse = function (url) {
	var parser = document.createElement("a");
	parser.href = url;
	
	// IE 8 and 9 dont load the attributes "protocol" and "host" in case the source URL
	// is just a pathname, that is, "/example" and not "http://domain.com/example".
	parser.href = parser.href;
	
	// IE 7 and 6 wont load "protocol" and "host" even with the above workaround,
	// so we take the protocol/host from window.location and place them manually
	if (parser.host === "") {
		var newProtocolAndHost = window.location.protocol + "//" + window.location.host;
		if (url.charAt(1) === "/") {
			parser.href = newProtocolAndHost + url;
		} else {
			// the regex gets everything up to the last "/"
			// /path/takesEverythingUpToAndIncludingTheLastForwardSlash/thisIsIgnored
			// "/" is inserted before because IE takes it of from pathname
			var currentFolder = ("/"+parser.pathname).match(/.*\//)[0];
			parser.href = newProtocolAndHost + currentFolder + url;
		}
	}
	
	// copies all the properties to this object
	var properties = ['host', 'hostname', 'hash', 'href', 'port', 'protocol', 'search'];
	for (var i = 0, n = properties.length; i < n; i++) {
	  this[properties[i]] = parser[properties[i]];
	}
	
	// pathname is special because IE takes the "/" of the starting of pathname
	this.pathname = (parser.pathname.charAt(0) !== "/" ? "/" : "") + parser.pathname;
}

ParsedUrl.prototype.set = function (attr_name, attr_value) {
	this[attr_name] = attr_value;
	this.parse(this.toString());
}

ParsedUrl.prototype.toString = function () {
	return (this.protocol || "http:") + "//" + this.hostname +
		((this.port) ? ":" + this.port : "") + 
		((this.pathname) ? this.pathname : "/") + 
		((this.search) ? this.search : "") + 
		((this.hash) ? this.hash : "");
}

// Use:
var myUrl = new ParsedUrl("http://www.example.com:8080/path?query=123#fragment");

Usage: prototype.set and prototype.toString

var myUrl = new ParsedUrl("http://www.example.com:8080/path?query=123#fragment");
myUrl.set("hostname", "www.google.com");
myUrl.toString();

Result:

http://www.google.com:8080/path?query=123#fragment