水平Javascript菜单错误

Question

我的JavaScript菜单存在一个小问题。

当我选择一个项目时，它始终显示最后一个子菜单。

对于Javascript专业人士来说，这非常简单：p

以下是样本：

CSS

ul#midnav {
    border-width: 1px 0;
    list-style: none;
    margin-bottom: 5px;
    text-align: center;
    border-bottom: solid thin #c8c8c8;
    padding: 0px 0px 13px 0px;
}
ul#midnav li {
    display: inline;
    padding: 0px 0px;
}
ul#midnav li a {
    text-transform:uppercase;
    font-size:11px;
    padding: 5px 13px 0px 5px;
    background: url('../image/arrow-topdown-gray.png') 100% 9px no-repeat;
}
ul#midnav li ul {
    line-height: 28px;
    padding: 0;
    position: absolute;
    top: -30px;
    background: none;
    display: none;
    /* --Hide by default--*/
    width: 960px;
    height:28px;
    background: #fff;
    border-top: solid thin #eeeeed;
}
ul#midnav li ul a {
    background: url('../image/arrow-left-gray.png') 100% 9px no-repeat;
}

HTML

<div id="navigation">
    <div id="mid-nav">
        <ul id="midnav">
            <li><a href="#">Item 1</a> 
                <ul>
                    <li><a href="#">Item 1.1</a>
                    </li>
                    <li><a href="#">Item 1.2</a>
                    </li>
                </ul>
            </li>
            <li><a href="#">Item 2</a> 
                <ul>
                    <li><a href="#">Item 2.1</a>
                    </li>
                    <li><a href="#">Item 2.2</a>
                    </li>
                </ul>
            </li>
            <li><a href="#">Item 3</a> 
                <ul>
                    <li><a href="#">Item 3.1</a>
                    </li>
                    <li><a href="#">Item 3.2</a>
                    </li>
                </ul>
            </li>
            <li><a href="#">Item 4</a> 
                <ul>
                    <li><a href="#">Contact Us</a>
                    </li>
                    <li><a href="#">Item 4.1</a>
                    </li>
                    <li><a href="#">Item 4.2</a>
                    </li>
                </ul>
            </li>
            <li><a href="#">Item 5</a> 
                <ul>
                    <li><a href="#">Item 5.1</a>
                    </li>
                    <li><a href="#">Item 5.2</a>
                    </li>
                </ul>
            </li>
        </ul>
    </div>
</div>
</div>    

的JavaScript

$(document).ready(function () {
    $('ul#midnav li a').on('click', function (event) {
        event.preventDefault();
        $('#mid-nav > ul').find('ul').slideUp(function () {
            $(this).closest('li').find('ul').slideToggle();
        });
    });
});

Answer 1

this处理程序中的

ready引用了错误的对象：

    $(document).ready(function () {
      $('ul#midnav li a').on('click', function(event){
        event.preventDefault();

        var e=this;
            // must alias or 'this' will refer to
            // the last submenu slid into hiding
            // instead of the one to open

        $('#mid-nav > ul').find('ul').slideUp(
          function(){
            $(e).closest('li').find('ul').slideToggle(); // 'e' instaed of 'this'
        });

      });
    });