JS+Css 实现页脚DIV块始终保持在页面底部的方法

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要实现的功能:无论将浏览器拖大或拉小,将页脚DIV块保持在页面底部
1、将Javascript代码和DIV/CSS代码写在同一个文件里:经测试代码如下:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<Meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>让页脚保持在未满屏页面底部</title>
<!--DIV块的css-->
<style type="text/css">
*{margin:0;padding:0;}
#top{background:#33CCFF;text-align:center;}
#bottom{background:#FFCC00;text-align:center;width:100%;}
</style>

</head>

<body>
<div id="top">top</div>
<div id="bottom">bottom</div>
<!--javascript代码,之所以写在后面,是为了等完全加载top和bottom的DIV块后,便于代码读取相关信息-->
<script language="javascript" type="text/javascript">
function calcDistance(){
var topHeight = document.getElementById("top").scrollHeight;
var bottomHeight = document.getElementById("bottom").scrollHeight;
var allHeight = document.documentElement.clientHeight;
var bottom = document.getElementById("bottom");
if((topHeight + bottomHeight) < allHeight){
bottom.style.position = "absolute";
bottom.style.bottom = "0";
}else{
bottom.style.position = "";
bottom.style.bottom = "";
} 
setTimeout(function(){calcDistance();},10);
}
calcDistance();
</script>

</body>
</html>
2、将Html、DIV/CSS、Javascript分别写在不同的文件里:html文件index.html(其中调用了index.js和index.css):

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<Meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>让页脚保持在未满屏页面底部</title>
<link href="index.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" language="javascript" src="index.js"></script>
</head>

<body>
<div id="top">top</div>
<div id="bottom">bottom</div>
<script language="javascript" type="text/javascript">
calcDistance();
</script>
</body>
</html>
index.css文件

@charset "utf-8";
/* CSS Document */
*{
    margin:0;
    padding:0;
}
#top{
    background:#33CCFF;
    text-align:center;
}
#bottom{
    background:#FFCC00;
    text-align:center;
    width:100%;
}
注意:此处最好给出top和bottom两个DIV块的高度,便于javascript代码计算,有的情况下(比如top块中包含其它DIV块时,可能会造成有的浏览器下计算不准确) index.js文件

// JavaScript Document
function calcDistance(){
var topHeight = document.getElementById("top").scrollHeight;
var bottomHeight = document.getElementById("bottom").scrollHeight;
var allHeight = document.documentElement.clientHeight;
var bottom = document.getElementById("bottom");
if((topHeight + bottomHeight) < allHeight){
bottom.style.position = "absolute";
bottom.style.bottom = "0";//设置距底部距离时如果用数字apx出错,则试试apx
}else{
bottom.style.position = "";
bottom.style.bottom = "";
} 
setTimeout(function(){calcDistance();},10);
}
3、如果想底栏DIV块距离其之上最后一个DIV块的最小距离为A(假设为150px),那么只需修改index.js文件即可,修改如下:

// JavaScript Document
function calcDistance(){
var topHeight = document.getElementById("top").scrollHeight;
var bottomHeight = document.getElementById("bottom").scrollHeight;
var allHeight = document.documentElement.clientHeight;
var bottom = document.getElementById("bottom");
if((topHeight + bottomHeight + 150) < allHeight){
bottom.style.position = "absolute";
bottom.style.bottom = "0";
bottom.style.top = "";
}else{
bottom.style.position = "relative";
bottom.style.bottom = "";
bottom.style.top = "150px";//距离上一个DIV块150像素,如果用150px达不到想要的结果,则试试150(去掉px)
} 
setTimeout(function(){calcDistance();},10);
}
效果图(两个DIV块之间距离小于150像素时,垂直滚动条出现):
原文链接:https://www.f2er.com/js/527806.html

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