Implementing folding menu based on HTML5 code with source code download_html5 tutorial skills

(function ($) {
var cards = $('.card-drop'), toggler = cards.find('.toggle'), links = cards.find('ul>li>a'), li = links.parent('li') , count = links.length, width = 100;
li.each(function (i) {
$(this).css('z-index', count - i);
});
function setClosed() {
li.each(function (index) {
$(this).css('top', index * 4).css('width', width - index * 0.5 '%').css('margin-left', index * 0.25 '%');
});
li.addClass('closed');
toggler.removeClass('active') ;
}
setClosed();
toggler.on('mousedown', function () {
var $this = $(this);
if ($this.is(' .active')) {
setClosed();
} else {
$this.addClass('active');
li.removeClass('closed');
li.each (function (index) {
$(this).css('top', 60 * (index 1)).css('width', '100%').css('margin-left', '0px ');
});
}
});
links.on('click', function (e) {
var $this = $(this), label = $ this.data('label');
icon = $this.children('i').attr('class');
li.removeClass('active');
if ($this .parent('li').is('active')) {
$this.parent('li').removeClass('active');
} else {
$this.parent( 'li').addClass('active');
}
toggler.children('span').text(label);
toggler.children('i').removeClass().addClass (icon);
setClosed();
e.preventDefault;
});
}(jQuery));