javascript url parameter받기

function get_param(str)
{
	var res = "", tmp = "";
	var params = location.search.substr(location.search.indexOf("?") + 1);
	params = params.split("&");
	
	for(var i = 0; i < params.length; i++)
	{
		tmp = params[i].split("=");
		if(tmp[0]  == str) {res = tmp[1];}
	}
	return res;
}

console.log(get_param("변수명"));