实现随滚动条滚动效果的两个版本jQuery代码

//侧栏随动
var rollStart = $('.feed-mail'), //滚动到此区块的时候开始随动
	rollOut = $('.cookie-list'); //隐藏rollStart之后的区块
 
rollStart.before('<div class="da_rollbox"></div>');
 
var offset = rollStart.offset(),objWindow = $(window),rollBox = rollStart.prev(),
	rollSet = $('.search,.weibo,.group'); //添加rollStart之前的随动区块
 
objWindow.scroll(function() {
	if (objWindow.scrollTop() > offset.top){
		if(rollBox.html(null)){
			rollSet.clone().prependTo('.da_rollbox');
		}
		rollOut.fadeOut();
		rollBox.show().stop().animate({marginTop: objWindow.scrollTop() - offset.top + 20},400);
	} else {
		rollOut.fadeIn();
		rollBox.hide().stop().animate({marginTop:0},400);
	}
});

//侧栏随动
var rollStart = $('.feed-mail'), //滚动到此区块的时候开始随动
	rollSet = $('.search,.weibo,.group,.feed-mail,.tags'); //添加rollStart之前的随动区块
 
rollStart.before('<div class="da_rollbox" style="position:fixed;background-color:#fff;width:inherit;"></div>');
var offset = rollStart.offset(),objWindow = $(window),rollBox = rollStart.prev();
objWindow.scroll(function() {
	if (objWindow.scrollTop() > offset.top){
		if(rollBox.html(null)){
			rollSet.clone().prependTo('.da_rollbox');
		}
		rollBox.show().stop().animate({top:0,paddingTop:15},400);
	} else {
		rollBox.hide().stop().animate({top:0},400);
	}
});