jquery下拉效果导航栏插件

jquery下拉效果导航栏插件,鼠标移动到导航上,会从下面降下一面"锦旗"效果的背景.
1、在head加入css代码:

<style>
body, div, h1, h2, h3, h4, h5, h6, p, ul, ol, li, dl, dt, dd, img, form, fieldset, input, textarea, blockquote {
    margin: 0; padding: 0; border: 0;
}
body {
    background: #f5f0e0 url(img/noise.png);
}
#container {
    height: 800px;
    background: url(img/bg.jpg) center top no-repeat;
}
ul#nav {
    width: 700px; margin: 0 auto; text-align: center; overflow: hidden;
}
    ul#nav li {
    float: left; list-style: none;
}
ul#nav li a {
    display: block; width: 97px; height: 77px;
    padding: 72px 0 0 0; margin: 0 32px 0 32px;
    font: bold 16px Helvetica, Arial, Sans-Serif; text-transform: uppercase;
    color: #9c5959; text-shadow: 0 1px 3px #c4bda6; text-decoration: none;
    background: url(img/label.png) 0 -149px no-repeat;
}
    ul#nav li a:hover {
    background: url(img/label.png) 0 0 no-repeat;
    color: #eee9d9; text-shadow: 0 2px 3px #4c2222;
}
ul#nav li a.js:hover {
    background: url(img/label.png) 0 -149px no-repeat;
}
</style>

2、在head加入js代码:

<script src="http://www.5imoban.net/download/jquery/jquery-1.4.2.min.js" type="text/javascript"></script>
<script type="text/javascript">
(function($) {
    if(!document.defaultView || !document.defaultView.getComputedStyle){ // IE6-IE8
        var oldCurCSS = jQuery.curCSS;
        jQuery.curCSS = function(elem, name, force){
            if(name === 'background-position'){
                name = 'backgroundPosition';
            }
            if(name !== 'backgroundPosition' || !elem.currentStyle || elem.currentStyle[ name ]){
                return oldCurCSS.apply(this, arguments);
            }
            var style = elem.style;
            if ( !force && style && style[ name ] ){
                return style[ name ];
            }
            return oldCurCSS(elem, 'backgroundPositionX', force) +' '+ oldCurCSS(elem, 'backgroundPositionY', force);
        };
    }
    var oldAnim = $.fn.animate;
    $.fn.animate = function(prop){
        if('background-position' in prop){
            prop.backgroundPosition = prop['background-position'];
            delete prop['background-position'];
        }
        if('backgroundPosition' in prop){
            prop.backgroundPosition = '('+ prop.backgroundPosition;
        }
        return oldAnim.apply(this, arguments);
    };
    function toArray(strg){
        strg = strg.replace(/left|top/g,'0px');
        strg = strg.replace(/right|bottom/g,'100%');
        strg = strg.replace(/([0-9\.]+)(\s|\)|$)/g,"$1px$2");
        var res = strg.match(/(-?[0-9\.]+)(px|\%|em|pt)\s(-?[0-9\.]+)(px|\%|em|pt)/);
        return [parseFloat(res[1],10),res[2],parseFloat(res[3],10),res[4]];
    }
    $.fx.step. backgroundPosition = function(fx) {
        if (!fx.bgPosReady) {
            var start = $.curCSS(fx.elem,'backgroundPosition');
            if(!start){//FF2 no inline-style fallback
                start = '0px 0px';
            }
            start = toArray(start);
            fx.start = [start[0],start[2]];
            var end = toArray(fx.options.curAnim.backgroundPosition);
            fx.end = [end[0],end[2]];
            fx.unit = [end[1],end[3]];
            fx.bgPosReady = true;
        }
        var nowPosX = [];
        nowPosX[0] = ((fx.end[0] - fx.start[0]) * fx.pos) + fx.start[0] + fx.unit[0];
        nowPosX[1] = ((fx.end[1] - fx.start[1]) * fx.pos) + fx.start[1] + fx.unit[1];           
        fx.elem.style.backgroundPosition = nowPosX[0]+' '+nowPosX[1];
    };
})(jQuery);
$(document).ready(function() {
    $("ul#nav li a").addClass("js");
    $("ul#nav li a").hover(
      function () {
        $(this).stop(true,true).animate({backgroundPosition:"(0 0)"}, 200);
        $(this).animate({backgroundPosition:"(0 -5px)"}, 150);
      },
      function () {
        $(this).animate({backgroundPosition:"(0 -149px)"}, 200);

      }
    );
});
</script>

3、在导航地方加入下面的代码:

<div id="container">
    <ul id="nav">
        <li><a href="http://www.5imoban.net" title="我爱模板网首页">Home</a></li>
        <li><a href="http://www.5imoban.net/about/" title="关于我爱模板网">About</a></li>
        <li><a href="http://www.5imoban.net/psdmoban/" title="PSD网站模板">PDS模板</a></li>
        <li><a href="http://www.5imoban.net/contact/" title="联系我爱模板网">Contact</a></li>
    </ul>
</div>

注: 如果觉得js和css放在页面太多,建议新建js和css文件,将代码放到里面,然后再引入即可.