function add_GETParam(url, param, val, clearOthers) {
	

	if(clearOthers) {
		document.location = url + '?' + param + '=' + val;
	} else {
		
		if(url.indexOf('?') > 0) {
			
				if(url.indexOf(param+'=') > 0) {
					
						var reg = new RegExp(param+'=[0-9]+')
						var url = url.replace(reg, param+'='+val);
						
						document.location = url;
						
					} else {
					document.location = url + '&' + param + '=' + val;
				}
		
		} 
		
		else document.location = url + '?' + param + '=' + val;
	
	}
	
}