移动网页端滑动到底部加载数据

$(window).bind("scroll", function () {    var flag=document.getElementById('flag').value;    if(getScrollHeight() == getDocumentTop() + getWindowHeight()){        //当滚动条到底时,这里是触发内容        //异步请求数据,局部刷新dom        //ajax_function()        if(flag==1) {            document.getElementById('flag').value=0;            alert("滑动到的底部");        }    }});//文档高度function getDocumentTop() {    var scrollTop =  0, bodyScrollTop = 0, documentScrollTop = 0;    if (document.body) {        bodyScrollTop = document.body.scrollTop;    }    if (document.documentElement) {        documentScrollTop = document.documentElement.scrollTop;    }    scrollTop = (bodyScrollTop - documentScrollTop > 0) ? bodyScrollTop : documentScrollTop;    console.log("scrollTop:"+scrollTop);    return scrollTop;}//可视窗口高度function getWindowHeight() {    var windowHeight = 0;    if (document.compatMode == "CSS1Compat") {        windowHeight = document.documentElement.clientHeight;    } else {        windowHeight = document.body.clientHeight;    }    console.log("windowHeight:"+windowHeight);    return windowHeight;}//滚动条滚动高度function getScrollHeight() {    var scrollHeight = 0, bodyScrollHeight = 0, documentScrollHeight = 0;    if (document.body) {        bodyScrollHeight = document.body.scrollHeight;    }    if (document.documentElement) {        documentScrollHeight = document.documentElement.scrollHeight;    }    scrollHeight = (bodyScrollHeight - documentScrollHeight > 0) ? bodyScrollHeight : documentScrollHeight;    console.log("scrollHeight:"+scrollHeight);    return scrollHeight;}