Get the search key of url

getUrlSearchKey.js

var getSearchKey = function(key){
	if (!location.search) return null;
	var list = location.search.split("?")[1].split("&");
	for (var i=0; i < list.length; ++i){
		if (!list[i]) continue;
		var dict = list[i].split("=");
		if (key == dict[0]){
			return dict[1]
		}
	}
	return null;
}