/* Client-side access to querystring name=value pairs
	Version 1.2.4
*/
function Querystring(qs) { // optionally pass a querystring to parse
	this.params = new Object();
	this.get=Querystring_get;
	this.construye=QueryString_construye;
	this.descarta=QueryString_descarta;
	
	if (qs == null)
		qs=location.search.substring(1,location.search.length);

	if (qs.length == 0) return;

	// Turn <plus> back to <space>
	// See: http://www.w3.org/TR/REC-html40/interact/forms.html#h-17.13.4.1
	qs = qs.replace(/\+/g, ' '); 
	var args = qs.split('&'); // parse out name/value pairs separated via &
	
// split out each name=value pair
	for (var i=0;i<args.length;i++) 
	{
		var value;
		var pair = args[i].split('=');
		var name = unescape(pair[0]);

		if (pair.length == 2)
			value = unescape(pair[1]);
		else
			value = name;
		
		this.params[name]=value;
	}
}

function Querystring_get(key, default_) {
	// This silly looking line changes UNDEFINED to NULL
	if (default_ == null) default_ = null;
	
	var value=this.params[key];
	if (value==null) value=default_;
	
	return value;
}


/**
 * Elimina del array el argumento pasado
 */
function QueryString_descarta(nombre)
{
	var nuevo=new Object();
	
	for(key in this.params)
	{
		if(key!=nombre)
			nuevo[key]=this.params[key];
	}
	
	this.params=nuevo;	
}

/**
 * Construye de nuevo la queryString (sin el ?)
 * @param {Object} descartados
 */
function QueryString_construye()
{
	var queryString='';
	var i=0;
	var n;
	
	for(key in this.params)
	{
		queryString+=key+'='+this.params[key]+'&';
	}
	queryString=queryString.substr(0,queryString.length-1);
	return queryString;
}