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   | <script> var scrolltotop={ 	setting:{ 		startline:100, //起始行 		scrollto:0, //滚动到指定位置 		scrollduration:400, //滚动过渡时间 		fadeduration:[500,100] //淡出淡现消失 	}, 	controlHTML:'<img src="top.png" style="width:53px; height:53px; border:0;" />', //返回顶部按钮 	controlattrs:{offsetx:0,offsety:323},//返回按钮固定位置 	anchorkeyword:"#top", 	state:{ 		isvisible:false, 		shouldvisible:false 	},scrollup:function(){ 		if(!this.cssfixedsupport){ 			this.$control.css({opacity:0}); 		} 		var dest=isNaN(this.setting.scrollto)?this.setting.scrollto:parseInt(this.setting.scrollto); 		if(typeof dest=="string"&&jQuery("#"+dest).length==1){ 			dest=jQuery("#"+dest).offset().top; 		}else{ 			dest=0; 		} 		this.$body.animate({scrollTop:dest},this.setting.scrollduration); 	},keepfixed:function(){ 		var $window=jQuery(window); 		var controlx=$window.scrollLeft()+$window.width()-this.$control.width()-this.controlattrs.offsetx; 		var controly=$window.scrollTop()+$window.height()-this.$control.height()-this.controlattrs.offsety; 		this.$control.css({left:controlx+"px",top:controly+"px"}); 	},togglecontrol:function(){ 		var scrolltop=jQuery(window).scrollTop(); 		if(!this.cssfixedsupport){ 			this.keepfixed(); 		} 		this.state.shouldvisible=(scrolltop>=this.setting.startline)?true:false; 		if(this.state.shouldvisible&&!this.state.isvisible){ 			this.$control.stop().animate({opacity:1},this.setting.fadeduration[0]); 			this.state.isvisible=true; 		}else{ 			if(this.state.shouldvisible==false&&this.state.isvisible){ 				this.$control.stop().animate({opacity:0},this.setting.fadeduration[1]); 				this.state.isvisible=false; 			} 		} 	},init:function(){ 		jQuery(document).ready(function($){ 			var mainobj=scrolltotop; 			var iebrws=document.all; 			mainobj.cssfixedsupport=!iebrws||iebrws&&document.compatMode=="CSS1Compat"&&window.XMLHttpRequest; 			mainobj.$body=(window.opera)?(document.compatMode=="CSS1Compat"?$("html"):$("body")):$("html,body"); 			mainobj.$control=$('<div id="topcontrol">'+mainobj.controlHTML+"</div>").css({position:mainobj.cssfixedsupport?"fixed":"absolute",top:mainobj.controlattrs.offsety,right:mainobj.controlattrs.offsetx,opacity:0,cursor:"pointer"}).attr({title:"返回顶部"}).click(function(){mainobj.scrollup();return false;}).appendTo("body");if(document.all&&!window.XMLHttpRequest&&mainobj.$control.text()!=""){mainobj.$control.css({width:mainobj.$control.width()});}mainobj.togglecontrol(); 			$('a[href="'+mainobj.anchorkeyword+'"]').click(function(){mainobj.scrollup();return false;}); 			$(window).bind("scroll resize",function(e){mainobj.togglecontrol();}); 		}); 	} }; scrolltotop.init(); </script>
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