function getUrlVars()
{    
	var vars = [], hash;
	if (window.location.href.indexOf('?')>0)
	{
		var hashes = window.location.href.slice(window.location.href.indexOf('?') + 1).split('&');    
		for(var i = 0; i < hashes.length; i++)    
		{        
			hash = hashes[i].split('=');        
			vars.push(hash[0]);        
			vars[hash[0]] = hash[1];    
		}    
	}
	return vars;
}

function reParam(param_name, value)
{

	var url = window.location.protocol+window.location.pathname+'?';
	var params = getUrlVars();
	
	for (var i = 0; i < params.length; i++)
	{
		
		if (params[i]=='')
		{
		}
		else if (params[i]==param_name)
		{

		}
		else
		{
		  url = url + params[i] + '=' + params[params[i]] + '&';

		}
	}
        url = url + param_name+'=' + value + '&';
	window.location = url;

}