javascript 滑动底部加载事件

// 自定义事件
	function ajax_function() {
	    //alert("自定义事件内容");
	    getMore();
	}

	var timeoutInt;   // 要保证最后要运行一次
	window.onscroll = function () {
	    setTimeout(function () {
	        if (timeoutInt != undefined) {
	            window.clearTimeout(timeoutInt);
	        }
	        timeoutInt = window.setTimeout(function () {
	            //监听事件内容
	            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()
	            }
	        }, 105);
	    }, 100);
	}

	//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;
	}