code: function bindMenuItemShortcuts(menuItem, type) {
  	    var _this2 = this;
  
  	    // Navigate through menus via arrow keys and space
  	    on(menuItem, 'keydown keyup', function (event) {
  	      // We only care about space and ⬆️ ⬇️️ ➡️
  	      if (![32, 38, 39, 40].includes(event.which)) {
  	        return;
  	      } // Prevent play / seek
  
  
  	      event.preventDefault();
  	      event.stopPropagation(); // We're just here to prevent the keydown bubbling
  
  	      if (event.type === 'keydown') {
  	        return;
  	      }
  
  	      var isRadioButton = matches$1(menuItem, '[role="menuitemradio"]'); // Show the respective menu
  
  	      if (!isRadioButton && [32, 39].includes(event.which)) {
  	        controls.showMenuPanel.call(_this2, type, true);
  	      } else {
  	        var target;
  
  	        if (event.which !== 32) {
  	          if (event.which === 40 || isRadioButton && event.which === 39) {
  	            target = menuItem.nextElementSibling;
  
  	            if (!is$1.element(target)) {
  	              target = menuItem.parentNode.firstElementChild;
  	            }
  	          } else {
  	            target = menuItem.previousElementSibling;
  
  	            if (!is$1.element(target)) {
  	              target = menuItem.parentNode.lastElementChild;
  	            }
  	          }
  
  	          setFocus.call(_this2, target, true);
  	        }
  	      }
  	    }, false); // Enter will fire a `click` event but we still need to manage focus
  	    // So we bind to keyup which fires after and set focus here
  
  	    on(menuItem, 'keyup', function (event) {
  	      if (event.which !== 13) {
  	        return;
  	      }
  
  	      controls.focusFirstMenuItem.call(_this2, null, true);
  	    });
  	  }
docs: Bind keyboard shortcuts for a menu item We have to bind to keyup otherwise Firefox triggers a click when a keydown event handler shifts focus https://bugzilla.mozilla.org/show_bug.cgi?id=1220143