text: 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="' + mkSiteInfo.siteUrl + '/images/topback.gif" style="width:54px; height:54px; border:0;" />', //返回顶部按钮
  	controlattrs:{offsetx:30,offsety:80},//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=$('<div id="topcontrol">'+mainobj.controlHTML+"</div>").css({position:mainobj.cssfixedsupport?"fixed":"absolute",bottom:mainobj.controlattrs.offsety,right:mainobj.controlattrs.offsetx,opacity:0,cursor:"pointer"}).attr({title:"返回顶部"}).click(function(){mainobj.scrollup();return false;}).appendTo("body");if(document.all&&!window.XMLHttpRequest&&mainobj.$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();