$(document).ready(function () {
    var btn = $('#button');

    $(window).scroll(function () {
        if ($(window).scrollTop() > 500) {
            btn.addClass('show');
        } else {
            btn.removeClass('show');
        }
    });

    btn.on('click', function (e) {
        e.preventDefault();
        $('html, body').animate({ scrollTop: 0 }, '300');
    });
	
	// dropdown top menu on hover
	$('.dropdown').hover( function() { $(this).toggleClass('hover'); } );
	function toggleDropdown (e) {
		const _d = $(e.target).closest('.dropdown'),
		_m = $('.dropdown-menu', _d);
		setTimeout(function(){
			const shouldOpen = e.type !== 'click' && _d.hasClass('hover') /*&& _d.is(':hover')*/;
			_m.toggleClass('show', shouldOpen);
			_d.toggleClass('show', shouldOpen);
			$('[data-toggle="dropdown"]', _d).attr('aria-expanded', shouldOpen);
		}, e.type === 'mouseleave' ? 300 : 0);
	}
	$('body')
		.on('mouseenter mouseleave','.dropdown',toggleDropdown)
		.on('click', '.dropdown-menu a', toggleDropdown);

});