【JavaScript】URLのパラメータの取得

function getParameter(name, url) {
        if (!url) url = window.location.href;
	name = name.replace(/[\[\]]/g, "\\$&");
	var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)");
	results = regex.exec(url);
	if (!results) return null;
	if (!results[2]) return '';
	return decodeURIComponent(results[2].replace(/\+/g, " "));
	}