Here's the JS that worked after some tweaking and valid input:
$(document).ready(function(){
$('#global_nav > ul').toggleClass('no-js js');
var menuList = $(".js").find("li");
menuList.find("ul").hide();
menuList.on("click", function(){
menuList.find("ul").slideUp(400);
if (!($(this).find("ul").is(":visible"))) {
menuList.removeClass("selected");
$(this).find("ul").slideDown(400);
$(this).addClass("selected");
};
});
});