//回到顶部开始
var scrolltotop={
setting: {startline:1, scrollto: 0, scrollduration:1000, fadeduration:[500, 100]},
controlhtml: '',
controlattrs: {offsetx:5, offsety:80},
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=$('