<section class="main">
 <div class="wrapper-demo">
 <div id="dd" class="wrapper-dropdown-1" tabindex="1">
 <span>手册网</span>
 <ul class="dropdown" tabindex="">
 <li><a href="#">jQuery特效</a></li>
 <li><a href="#">网站模板</a></li>
 </ul>
 </div>
 </div>
 </section>
</div>
<script type="text/javascript" src="http://libs.useso.com/js/jquery/1.7.2/jquery.min.js"></script>
<script type="text/javascript">
 function DropDown(el) {
 this.dd = el;
 this.placeholder = this.dd.children('span');
 this.opts = this.dd.find('ul.dropdown > li');
 this.val = '';
 this.index = -;
 this.initEvents();
 }
 DropDown.prototype = {
 initEvents: function() {
 var obj = this;
 obj.dd.on('click', function(event) {
 $(this).toggleClass('active');
 return false;
 });
 obj.opts.on('click', function() {
 var opt = $(this);
 obj.val = opt.text();
 obj.index = opt.index();
 obj.placeholder.text('Gender: ' + obj.val);
 });
 },
 getValue: function() {
 return this.val;
 },
 getIndex: function() {
 return this.index;
}
 }
 $(function() {
 var dd = new DropDown($('#dd'));
 $(document).click(function() {
 $('.wrapper-dropdown-1').removeClass('active');
 });
 });
</script>