code: function trapFocus() {
  	  var element = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : null;
  	  var toggle = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : false;
  
  	  if (!is$1.element(element)) {
  	    return;
  	  }
  
  	  var focusable = getElements.call(this, 'button:not(:disabled), input:not(:disabled), [tabindex]');
  	  var first = focusable[0];
  	  var last = focusable[focusable.length - 1];
  
  	  var trap = function trap(event) {
  	    // Bail if not tab key or not fullscreen
  	    if (event.key !== 'Tab' || event.keyCode !== 9) {
  	      return;
  	    } // Get the current focused element
  
  
  	    var focused = document.activeElement;
  
  	    if (focused === last && !event.shiftKey) {
  	      // Move focus to first element that can be tabbed if Shift isn't used
  	      first.focus();
  	      event.preventDefault();
  	    } else if (focused === first && event.shiftKey) {
  	      // Move focus to last element that can be tabbed if Shift is used
  	      last.focus();
  	      event.preventDefault();
  	    }
  	  };
  
  	  toggleListener.call(this, this.elements.container, 'keydown', trap, toggle, false);
  	}
docs: Trap focus inside container