<script type="text/javascript">

        //当窗口滚动到一定高度时 某块页面开始加载数据

        window.onload = function()

        {

            var oHeader = document.getElementById("header");

            var height = oHeader.offsetHeight;

            window.onscroll = function(){

                //scrollTop的值

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

                //窗口可视化高度

                var clientHeight = document.documentElement.clientHeight || document.body.clientHeight;

                document.getElementById("txt1").value="scrollTop:"+scrollTop+",height:"+height;

                var oContent = document.getElementById("content");

                if(scrollTop+clientHeight >height)

                {

                   oContent.innerHTML = "<h1>正在加载中.....</h1>";

                   //延迟3秒执行

                   setTimeout(function(){

                     oContent.innerHTML = "<h1>scroll事件执行的代码块</h1>";

                     oContent.style.background="red";

                   },3000);  

                }

                else

                {

                    oContent.innerHTML="";

                    oContent.removeAttribute("style");

                }

            }

        }

    </script>