MooTools 页面滚动浮动层智能定位实现代码

HTML代码：

<div class="float" id="float"> 
我是个腼腆羞涩的浮动层... 
</div>

JS代码：

var $smartFloat = function(elements) { 
var position = function(element) { 
var top = element.getPosition().y, pos = element.getStyle("position"); 
window.addEvent("scroll", function() { 
var scrolls = this.getScroll().y; 
if (scrolls > top) { 
if (window.XMLHttpRequest) { 
element.setStyles({ 
position: "fixed", 
top: 0 
}); 
} else { 
element.setStyles({ 
top: scrolls 
}); 
} 
}else { 
element.setStyles({ 
position: "absolute", 
top: top 
}); 
} 
}); 
}; 
if ($type(elements) === "array") { 
return elements.each(function(items) { 
position(items); 
}); 
} else if ($type(elements) === "element") { 
position(elements); 
} 
}; //绑定 
$smartFloat($("float"));