var scrolltotop={
   //startline: Integer. Number of pixels from top of doc scrollbar is scrolled before showing control
   //scrollto: Keyword (Integer, or "Scroll_to_Element_ID"). How far to scroll document up when control is clicked on (0=top).
   setting: {startline:300, scrollto: 0, scrollduration:1000, fadeduration:[500, 100]},
   controlHTML: '', //HTML for control, which is auto wrapped in DIV w/ ID="topcontrol"
   controlattrs: {offsetx:5, offsety:5}, //offset of control relative to left/ bottom of window corner
   anchorkeyword: '#top', //Enter href value of HTML anchors on the page that should also act as "Scroll Up" links

   state: {isvisible:false, shouldvisible:false},

   scrollup:function(){
    if (!this.cssfixedsupport) //if control is positioned using JavaScript
     this.$control.css({opacity:0}) //hide control immediately after clicking it
    var dest=isNaN(this.setting.scrollto)? this.setting.scrollto : parseInt(this.setting.scrollto)
    if (typeof dest=="string" && jQuery('#'+dest).length==1) //check element set by string exists
     dest=jQuery('#'+dest).offset().top
    else
     dest=0
    this.$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($){
     var mainobj=scrolltotop
     var iebrws=document.all
     mainobj.cssfixedsupport=!iebrws || iebrws && document.compatMode=="CSS1Compat" && window.XMLHttpRequest //not IE or IE7+ browsers in standards mode
     mainobj.$body=(window.opera)? (document.compatMode=="CSS1Compat"? $('html') : $('body')) : $('html,body')
     mainobj.$control=$('')
      .css({position:mainobj.cssfixedsupport? 'fixed' : 'absolute', bottom:mainobj.controlattrs.offsety, left:mainobj.controlattrs.offsetx, opacity:0, cursor:'pointer'})
      .attr({title:'Up'})
      .click(function(){mainobj.scrollup(); return false})
      .appendTo('body')
     if (document.all && !window.XMLHttpRequest && mainobj.$control.text()!='') //loose check for IE6 and below, plus whether control contains any text
      mainobj.$control.css({width:mainobj.$control.width()}) //IE6- seems to require an explicit width on a DIV containing text
     mainobj.togglecontrol()
     $('a[href="' + mainobj.anchorkeyword +'"]').click(function(){
      mainobj.scrollup()
      return false
     })
     $(window).bind('scroll resize', function(e){
      mainobj.togglecontrol()
     })
    })
   }
}

scrolltotop.init()