随网页上下移动的返回顶部按钮如何实现

[tangguowei]

一开始按钮图片在一个位置，移动滚动条后，能上下移动,始终在一个固定区域移动用jquery怎么实现

如http://www.mofang.cn/_about/about.php右侧的top做法，

$(window).scroll(function (){
var oldTop = parseInt($('#gotop').css('top'));
var newTop = $(document).scrollTop() + 200;
$('#gotop').animate({top:newTop},10);
//alert(currentTop);
});
我这样写的效果不一样

[happy664618843]

  var advTop=0;
    function init()
    {
    advTop=document.getElementById("advlayer").style.pixelTop;
    
    }
    function move()
    {
     document.getElementById("advlayer").style.pixelTop=advTop+document.documentElement.scrollTop;
    }

[qqzeng-ip]

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=$('<div id="topcontrol">'+mainobj.controlHTML+'</div>')
				.css({position:mainobj.cssfixedsupport? 'fixed' : 'absolute', bottom:mainobj.controlattrs.offsety, right:mainobj.controlattrs.offsetx, opacity:0, cursor:'pointer'})
				.attr({title:'Scroll Back to Top'})
				.click(function(){mainobj.scrollup(); return false})
				.appendTo('body')
			if (document.all && !window.XMLHttpRequest && mainobj.$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()
			})
		})
	}
}

[xmliy]

对于IE7.0以上版本或其它标准浏览器，可以使用display:fixed来设置

[chen_xiangguo]

固定插件

[lijing1116]

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