(function($){
var goToTopTime;
$.fn.goToTop=function(options){
var opts = $.extend({},$.fn.goToTop.def,options);
var $window=$(window);
$body = (window.opera) ? (document.compatMode == "CSS1Compat" ? $('html') : $('body')) : $('html,body'); // opera fix
$(this).hide();
var $this=$(this);
clearTimeout(goToTopTime);
goToTopTime=setTimeout(function(){
var controlLeft;
if ($window.width() > opts.pageHeightJg * 2 + opts.pageWidth) {
controlLeft = ($window.width() - opts.pageWidth) / 2 + opts.pageWidth + opts.pageWidthJg;
}else{
controlLeft = $window.width()- opts.pageWidthJg-$this.width();
}
var cssfixedsupport=$.browser.msie && parseFloat($.browser.version) < 7;//判断是否ie6
var controlTop=$window.height() - $this.height()-opts.pageHeightJg;
controlTop=cssfixedsupport ? $window.scrollTop() + controlTop : controlTop;
var shouldvisible=( $window.scrollTop() >= opts.startline )? true : false;
if (shouldvisible){
$this.stop().show(opts.showBtntime);
}else{
$this.stop().hide(opts.showBtntime);
}
$this.css({
position: cssfixedsupport ? 'absolute' : 'fixed',
top: controlTop,
left: controlLeft
});
},500);
$(this).click(function(event){
$body.stop().animate( { scrollTop: $(opts.targetObg).offset().top}, opts.duration);
$(this).blur();
event.preventDefault();
event.stopPropagation();
});
};
$.fn.goToTop.def={
pageWidth:950,//页面宽度
pageWidthJg:10,//按钮和页面的间隔距离
pageHeightJg:50,//按钮和页面底部的间隔距离
startline:20,//出现回到顶部按钮的滚动条scrollTop距离
duration:200,//回到顶部的速度时间
showBtntime:100,//显示\隐藏回到顶部按钮的速度时间
targetObg:"body"//目标位置
};
})(jQuery);
$(function(){
$('<a href="#" class="go-top"><img src="images/go-top.png" alt="" /></a>').appendTo("body");
}); 
$(document).ready(function() {
  $(".company").click(function(){
		$(".branch").slideToggle("slow");
    $(".company").toggleClass("group") ;
    //$(".company a").toggleClass("bor_none") ;
  });
  $(".go-top").goToTop({});
  $(window).bind('scroll resize',function(){
      $(".go-top").goToTop({});
  });

});