jQuery动态背景的导航栏代码

<script type="text/javascript" src="http://www.5imoban.net/download/jquery/jquery-1.6.min.js" charset="utf-8"></script>
<script type="text/javascript">
$(document).ready(function(){
	var width = 0;
	$('#menu li').each(function() {
		width += $(this).width()+1;
	});
	var padding = parseInt((($('#menu').width() - width) / $('#menu li a').length)/2);
	var pixLeft = ($('#menu').width() - width)-(padding*$('#menu li a').length*2)
	$('#menu li a').each(function(index) {
		if (index+1 != $('#menu li a').length) {
			$(this).css('padding', '0 '+padding+'px');
			$(this).css('background-position', '-' + $(this).position().left + 'px 0');
		} else {
			padding = padding + (pixLeft/2);
			$(this).css('padding', '0 '+padding+'px');
			$(this).css('background-position', '-' + $(this).position().left + 'px 0');
		}
	});
	$('#menu li a').mouseover(function(){	
			$(this).stop().animate({ backgroundPosition: '-' + $(this).position().left - 129 + 'px 0'}, 2000)
		.mouseout(function(){
			$(this).stop().animate({ backgroundPosition: '-' + $(this).position().left + 'px 0'}, 2000)
		})
	});
});
(function($) {
	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);
			var end = toArray(fx.options.curAnim == undefined ? fx.end : fx.options.curAnim.backgroundPosition);
			fx.end = [end[0],end[2]];
			fx.unit = [end[1],end[3]];
			fx.bgPosReady = true;
		}
		//return;
		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);
</script>

<style type="text/css">
html {
	height:100%; 
	min-height:100%;
}
body {
	margin:0; padding:0;
	font-size:1em;
	font:62.8% Arial, Tahoma, Helvetica, sans-serif;
	background: #1e1e1d;
	color:#FFFFFF;
}
h1, h2, h3, h4, h5, h6, form, fieldset, dl, ul {margin:0; padding: 0;}
strong, b {font-weight:bold;}
em, i {font-style:italic;}
small {display:block;}
fieldset {border:0;}
img {border:none;}
a {
	color: #FFCC00;
	text-decoration: none;
}
a:hover {
	text-decoration: underline;
}
a:focus
{
 outline-style: none;
}
.go_back {
	position: absolute;
	top: 15px; left: 240px;
	color: #ff0072;
	font-size: 1.6em;
}
#menu {
	float: left;
	width: 800px;
	list-style: none;
	line-height: 33px;
	background: url('menu_bg1.gif') no-repeat top left;
	border-top: 1px solid #000;
	border-bottom: 1px solid #000;
	margin: 0;
	padding:0;
}
#menu li {
	float: left;
	border-left: 1px solid #000;
}
#menu li a {
	float: left;
	font-size: 1.2em;
	color: #fff;
	border-left: 1px solid #ccc;
	text-decoration: none;
	background: url('menu_bg1.gif') no-repeat top left;
}
#menu li a:hover {
	background: url('menu_bg_active.gif') no-repeat top left;
}
#menu li:first-child { border: none; }
#menu li:first-child a { border: none; }
</style>

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