【转】绝对定位：JS照样实现瀑布流式布局

一夜之间 似乎互联网上出现了一种类似瀑布形式的网页布局，如美丽说、蘑菇街等网站都采用这种布局形式。常见的实现方法一般分为：传统多列浮动 、CSS3 定义、绝对定位。 笔者看到网上仅仅有关于CSS的详细教程，未见有绝对定位的相关教程。现在想和各位朋友们分享一下绝对定位的应用及具体代码，希望朋友们能够指出其中的不足之处。

　　

　　JS的绝对定位分解成三个部分代码，这样清晰，方便查看代码，其中包括： Javascript代码、HTML代码、[AJax封装文件 代码。

 [Javaｓｃｒｉｐｔ]代码

<ｓｃｒｉｐｔ type="text/javaｓｃｒｉｐｔ" src="ajax.js"></ｓｃｒｉｐｔ>

<ｓｃｒｉｐｔ type="text/javaｓｃｒｉｐｔ">

window.onload=function()

{

        var oDiv =document.getElementById("div");

        var oUl=document.getElementsByTagName("ul");

        window.onscroll=function()

        {

                var clientH=document.documentElement.clientHeight;

                var scrollH=document.documentElement.scrollTop||document.body.scrollTop;

                for(var i=0;i<oUl.length;i++)

                {

                        var aLi=oUl[i].getElementsByTagName("li")

                        var lastL=aLi[aLi.length-1];

                        if(toTop(lastL)<clientH+scrollH)

                        {

                                ajax("a.js",function(str)

                                {

                                        var json = eval('('+str+')')

                                        for(var i=0;i<json.list.length;i++)

                                        {

                                                var list=json.list[i];

                                                for(var j=0;j<list.src.length;j++)

                                                {

                                                        var oLi=document.createElement("li")

                                                        oLi.innerHTML='<img src="'+list.src[j]+'"><p>'+list.title[j]+'</p>'

                                                        oUl[i].appendChild(oLi);

                                                }

                                        }

                                })

                        }

                }

        }

        function toTop(obj)

        {

                var top=0;

                while(obj)

                {

                        top +=obj.offsetTop;

                        obj=obj.offsetParent       

                }

                return top;

        }

}

</ｓｃｒｉｐｔ>

在html的head中，加入<ｓｃｒｉｐｔ src="js/*.js" type="text/javaｓｃｒｉｐｔ"></ｓｃｒｉｐｔ>

注：不能是<ｓｃｒｉｐｔ src="js/*.js" type="text/javaｓｃｒｉｐｔ"/>JS部分处理完毕之后，接下来就是HTML代码部分的书写：

 [HTML]代码

 <div id='div'>
                <ul>
                        <li>
                                <img src="images/1.jpg">
                                <p>11111111</p>
                        </li>
                        <li>
                                <img src="images/2.jpg">
                                <p>11111111</p>
                        </li>
                        <li>
                                <img src="images/3.jpg">
                                <p>11111111</p>
                        </li>
                        <li>
                                <img src="images/4.jpg">
                                <p>11111111</p>
                        </li>
                </ul>
                <ul>
                        <li>
                                <img src="images/5.jpg">
                                <p>11111111</p>
                        </li>
                        <li>
                                <img src="images/6.jpg">
                                <p>11111111</p>
                        </li>
                                        </ul>
        </div> 

 [AJax封装文件 ]代码

function ajax(url,sFn,nFn)
{
        var oAjax=null;
        if(window.ActiveXObject)
        {
                oAjax=new ActiveXObject("Microsoft.XMLHTTP")
        }
        else
        {
                oAjax=new XMLHttpRequest();
        }
        oAjax.open("GET",url,true)
        oAjax.send();
        oAjax.onreadystatechange=function()
        {
                if(oAjax.readyState==4)
                {
                        if(oAjax.status==200)
                        {
                                if(sFn)
                                {
                                        sFn(oAjax.responseText)
                                }
                        }
                        else
                        {
                                if(nFn)
                                {
                                        nFn(oAjax.status)
                                }
                        }
                }
        }
} 

    当然，通过JS调用做瀑布式布局的方法还有很多，笔者仅列出一种，除了JS，jQuery的Masonry插件、KISSY的waterfall插件等都可以更加方便的实现效果。JS+HTML+封装代码已经给写出来了，供大家参考。JS虽然老了，但依旧千变万化，希望你能找到最适合自己的方法。

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