jQuery实现多种动画效果的网站导航菜单

<!DOCTYPE html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk" />
<title>jQuery动态背景导航菜单</title>
<style type="text/css">
h2{clear: both;padding-top: 20px;}
ul{list-style: none;margin: 0;padding: 0;}
li{float: left;width: 100px;margin: 0;padding: 0;text-align: center;}
li a{display: block;padding: 5px 10px;height: 100%;color: #FFF;text-decoration: none;border-right: 1px solid #FFF;}
li a{background: url(images/bg2.jpg) repeat 0 0;}
li a: hover, li a: focus, li a: active{background-position: -150px 0;}
#a a{background: url(images/bg.jpg) repeat -20px 35px;}
#b a{background: url(images/bg2.jpg) repeat 0 0;}
#c a{background: url(images/bg3.jpg) repeat 0 0;}
#d a{background: url(images/bg4.jpg) repeat 0 0;}
</style>
<script type="text/javascript" src="jquery-1.6.2.min.js"></script>
<script type="text/javascript">
(function($) {
 $.extend($.fx.step,{
  backgroundPosition: function(fx) {
  if (fx.state === 0 && typeof fx.end == 'string') {
  var start = $.curCSS(fx.elem,'backgroundPosition');
  start = toArray(start);
  fx.start = [start[0],start[2]];
  var end = toArray(fx.end);
  fx.end = [end[0],end[2]];
  fx.unit = [end[1],end[3]];
   }
  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];
  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]];
  }
 }
 });
})(jQuery);
</script>
<script type="text/javascript">
$(function(){
 $('#a a')
  .css( {backgroundPosition: "-20px 35px"} )
  .mouseover(function(){
   $(this).stop().animate({backgroundPosition:"(-20px 94px)"}, {duration:500})
  })
  .mouseout(function(){
   $(this).stop().animate({backgroundPosition:"(40px 35px)"}, {duration:200, complete:function(){
    $(this).css({backgroundPosition: "-20px 35px"})
   }})
  })
 $('#b a')
  .css( {backgroundPosition: "0 0"} )
  .mouseover(function(){
   $(this).stop().animate({backgroundPosition:"(-150px 0)"}, {duration:500})
  })
  .mouseout(function(){
   $(this).stop().animate({backgroundPosition:"(-300px 0)"}, {duration:200, complete:function(){
    $(this).css({backgroundPosition: "0 0"})
   }})
  })
 $('#c a')
  .css( {backgroundPosition: "0 0"} )
  .mouseover(function(){
   $(this).stop().animate({backgroundPosition:"(0 -250px)"}, {duration:500})
  })
  .mouseout(function(){
   $(this).stop().animate({backgroundPosition:"(0 0)"}, {duration:500})
  })
 $('#d a')
  .css( {backgroundPosition: "0 0"} )
  .mouseover(function(){
   $(this).stop().animate({backgroundPosition:"(0 -250px)"}, {duration:500})
  })
  .mouseout(function(){
   $(this).stop().animate({backgroundPosition:"(0 0)"}, {duration:500})
  })
});
</script>
<meta http-equiv="Content-Type" content="text/html;charset=gbk">
</head>
<body>
<h1>jQuery Background Position</h1>
<h2>Example 0: No Script</h2>
 <ul id="noscript">
  <li><a href="#">Home</a></li>
  <li><a href="#">About</a></li>
  <li><a href="#">Contact</a></li>
 </ul>
<h2>Example A: Top down</h2>
 <ul id="a">
  <li><a href="#">Home</a></li>
  <li><a href="#">About</a></li>
  <li><a href="#">Contact</a></li>
 </ul>
<h2>Example B: Right left</h2>
 <ul id="b">
  <li><a href="#">Home</a></li>
  <li><a href="#">About</a></li>
  <li><a href="#">Contact</a></li>
 </ul>
<h2>Example C: Fade 1-colour</h2>
 <ul id="c">
  <li><a href="#">Home</a></li>
  <li><a href="#">About</a></li>
  <li><a href="#">Contact</a></li>
 </ul>
<h2>Example D: Fade 2-colour</h2>
 <ul id="d">
  <li><a href="#">Home</a></li>
  <li><a href="#">About</a></li>
  <li><a href="#">Contact</a></li>
 </ul>
</body>
</html>