Toggle named classes to elements with open/closed appended.

toggle-class.js

// toggleClass function
function toggleClass(elem, className) {
    if(elem.hasClass(className + '-open')) {
      elem.removeClass(className + '-open');
      elem.addClass(className + '-closed');
    } else if(elem.hasClass(className + '-closed')) {
      elem.removeClass(className + '-closed');
      elem.addClass(className + '-open');
    } else {
      elem.addClass(className + '-open');
    }
}

// standard button event
closeFilters.click(function() {
  toggleClass(html, 'filters');
});

// <a> click event
toggleModal.click(function( event ) {
  event.preventDefault(); /* include for links */
	toggleClass(html, 'overlay');
});