I am trying to create a really simple drop down menu.

I have one accordian button (labelled 'menu') that when clicked, opens up the dropdown menu.
However, when you click 'menu' (once the dropdown is open) the dropdown closes up then opens again. How can I change the script below so that when the menu button is clicked it either opens the menu if it's closed or closes it if it is open?

$(document).ready(function() {
	$('div.accordionButton').click(function() {