转 document.documentElement与document.body

zoukankan html css js c++ java

转 document.documentElement与document.body
原来HTML里是document.body
XHTML里是document.documentElement
都指的是<body>节点(OR元素)

可以这样兼容：

function getBodyObj()
{
return (document.documentElement) ? document.documentElement : document.body ;
}

在DHTML文档中对documentElement的说明是：Object that receives the reference to the document element，The root node of a typical HTML document is the html object.

body
Microsoft^® Internet Explorer 6 的新增内容
当你使用 !DOCTYPE 声明指定标准兼容模式的时候，此对象将不再代表文档内容所渲染的整个表面。该对象当然可从其内容中获得其大小，但你也可以像 div 对象那样精确设置其大小。

也就是说在HTML4.0标准下用document.body，在XHTML标准下就要换成document.documentElement。XHTML下document.body仅仅表示body对象，而不能代表文档内容所渲染的整个表面。HTML下document.body.clientHeight表示浏览器的可视高度，XHTML下则是document.documentElement.clientHeight。document.body.clientHeight在XHTML下仅表示body的可视高度。在HTML4.0下用document.body.scrollTop；而在XHTML下则是document.documentElement.scrollTop,之前的document.body.scrollTop是恒为0的。

===================================================================

IE6在页面内容超出窗口大小时将宽度属性scrollWidth、clientWidth、offsetWidth都解释为内容实际宽度。
上次的测试说明了document.body属性并不会给我们返回预期的结果，比如我们用document.body.clientHeight原本想取得“页面可见区域高度”，可实际上返回的是“页面实际内容高度”。
那我们怎么办呢？难道加上了文档DTD类型之后就再也不能取到“可见区域高度”和“内容实际宽度”等等属性了吗？

Java代码

<!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 runat="server">

<title>documentElement</title>

<style type="text/css">

body{margin:0;padding:0;font:12px/150% arial;}

</style>

<script type="text/javascript">

function a() {

var scrollTop;

var scrollLeft;

if (typeof window.pageYOffset != 'undefined') {

scrollTop = window.pageYOffset;

scrollLeft = window.pageXOffset;

}

else if (typeof document.compatMode != 'undefined' && document.compatMode != 'BackCompat') {

scrollTop = document.documentElement.scrollTop;

scrollLeft = document.documentElement.scrollLeft;

}

else if (typeof document.body != 'undefined') {

scrollTop = document.body.scrollTop;

scrollLeft = document.body.scrollLeft;

}

var scrollHeight = document.documentElement.scrollHeight;

var scrollWidth = document.documentElement.scrollWidth;

var clientWidth = document.documentElement.clientWidth;

var clientHeight = document.documentElement.clientHeight;

var offsetWidth = document.documentElement.offsetWidth;

var offsetHeight = document.documentElement.offsetHeight;

var screenTop = window.screenTop;

var screenBottom = window.screenBottom;

var screenLeft = window.screenLeft;

var sheight = window.screen.height;

var swidth = window.screen.width;

var availHeight = window.screen.availHeight;

var availWidth = window.screen.availWidth;

document.getElementById('scrollTop').value = scrollTop;

document.getElementById('scrollLeft').value = scrollLeft;

document.getElementById('scrollHeight').value = scrollHeight;

document.getElementById('scrollWidth').value = scrollWidth;

document.getElementById('clientWidth').value = clientWidth;

document.getElementById('clientHeight').value = clientHeight;

document.getElementById('offsetWidth').value = offsetWidth;

document.getElementById('offsetHeight').value = offsetHeight;

document.getElementById('screenTop').value = screenTop;

document.getElementById('screenBottom').value = screenBottom;

document.getElementById('screenLeft').value = screenLeft;

document.getElementById('sheight').value = sheight;

document.getElementById('swidth').value = swidth;

document.getElementById('availHeight').value = availHeight;

document.getElementById('availWidth').value = availWidth;

}

</script>

</head>

<body>

<div style="420px;height:470px;margin:0 auto;font-size:12px; border:solid 5px #ccc;">

<center>

<table width="400" border="0" cellspacing="0" cellpadding="0" style="font-size:12px;margin-top:20px;">

<tr>

<td width="187" align="right">scrollTop（滚动条卷过的高）：</td>

<td width="10"> </td>

<td width="209"><input type="text" name="scrollTop" id="scrollTop" /></td>

</tr>

<tr>

<td align="right">scrollLeft（滚动条卷过的宽）：</td>

<td> </td>

<td><input type="text" name="scrollLeft" id="scrollLeft" /></td>

</tr>

<tr>

<td align="right">scrollHeight（内容实际高度）：</td>

<td> </td>

<td><input type="text" name="scrollHeight" id="scrollHeight" /></td>

</tr>

<tr>

<td align="right">scrollWidth（内容实际宽度）：</td>

<td> </td>

<td><input type="text" name="scrollWidth" id="scrollWidth" /></td>

</tr>

<tr>

<td align="right">clientWidth（可见区域宽）：</td>

<td> </td>

<td><input type="text" name="clientWidth" id="clientWidth" /></td>

</tr>

<tr>

<td align="right">clientHeight（可见区域高）：</td>

<td> </td>

<td><input type="text" name="clientHeight" id="clientHeight" /></td>

</tr>

<tr>

<td align="right">offsetWidth（加滚动条宽？）：</td>

<td> </td>

<td><input type="text" name="offsetWidth" id="offsetWidth" /></td>

</tr>

<tr>

<td align="right">offsetHeight（加滚动条高？）：</td>

<td> </td>

<td><input type="text" name="offsetHeight" id="offsetHeight" /></td>

</tr>

<tr>

<td align="right">screenTop：</td>

<td> </td>

<td><input type="text" name="screenTop" id="screenTop" /></td>

</tr>

<tr>

<td align="right">screenBottom：</td>

<td> </td>

<td><input type="text" name="screenBottom" id="screenBottom" /></td>

</tr>

<tr>

<td align="right">screenLeft：</td>

<td> </td>

<td><input type="text" name="screenLeft" id="screenLeft" /></td>

</tr>

<tr>

<td align="right">sheight（分辨率高）：</td>

<td> </td>

<td><input type="text" name="sheight" id="sheight" /></td>

</tr>

<tr>

<td align="right">swidth（分分辨率宽）：</td>

<td> </td>

<td><input type="text" name="swidth" id="swidth" /></td>

</tr>

<tr>

<td align="right">availHeight：</td>

<td> </td>

<td><input type="text" name="availHeight" id="availHeight" /></td>

</tr>

<tr>

<td align="right">availWidth：</td>

<td> </td>

<td><input type="text" name="availWidth" id="availWidth" /></td>

</tr>

</table>

<a href="javascript:a()" style="height:20px;display:block;">内容高度是400PX，点击查看所有属性值</a>

</center>

</div>

</body>

</html>

<!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 runat="server"> <title>documentElement</title> <style type="text/css"> body{margin:0;padding:0;font:12px/150% arial;} </style> <script type="text/javascript"> function a() { var scrollTop; var scrollLeft; if (typeof window.pageYOffset != 'undefined') { scrollTop = window.pageYOffset; scrollLeft = window.pageXOffset; } else if (typeof document.compatMode != 'undefined' && document.compatMode != 'BackCompat') { scrollTop = document.documentElement.scrollTop; scrollLeft = document.documentElement.scrollLeft; } else if (typeof document.body != 'undefined') { scrollTop = document.body.scrollTop; scrollLeft = document.body.scrollLeft; } var scrollHeight = document.documentElement.scrollHeight; var scrollWidth = document.documentElement.scrollWidth; var clientWidth = document.documentElement.clientWidth; var clientHeight = document.documentElement.clientHeight; var offsetWidth = document.documentElement.offsetWidth; var offsetHeight = document.documentElement.offsetHeight; var screenTop = window.screenTop; var screenBottom = window.screenBottom; var screenLeft = window.screenLeft; var sheight = window.screen.height; var swidth = window.screen.width; var availHeight = window.screen.availHeight; var availWidth = window.screen.availWidth; document.getElementById('scrollTop').value = scrollTop; document.getElementById('scrollLeft').value = scrollLeft; document.getElementById('scrollHeight').value = scrollHeight; document.getElementById('scrollWidth').value = scrollWidth; document.getElementById('clientWidth').value = clientWidth; document.getElementById('clientHeight').value = clientHeight; document.getElementById('offsetWidth').value = offsetWidth; document.getElementById('offsetHeight').value = offsetHeight; document.getElementById('screenTop').value = screenTop; document.getElementById('screenBottom').value = screenBottom; document.getElementById('screenLeft').value = screenLeft; document.getElementById('sheight').value = sheight; document.getElementById('swidth').value = swidth; document.getElementById('availHeight').value = availHeight; document.getElementById('availWidth').value = availWidth; } </script> </head> <body> <div style="420px;height:470px;margin:0 auto;font-size:12px; border:solid 5px #ccc;"> <center> <table width="400" border="0" cellspacing="0" cellpadding="0" style="font-size:12px;margin-top:20px;"> <tr> <td width="187" align="right">scrollTop（滚动条卷过的高）：</td> <td width="10"> </td> <td width="209"><input type="text" name="scrollTop" id="scrollTop" /></td> </tr> <tr> <td align="right">scrollLeft（滚动条卷过的宽）：</td> <td> </td> <td><input type="text" name="scrollLeft" id="scrollLeft" /></td> </tr> <tr> <td align="right">scrollHeight（内容实际高度）：</td> <td> </td> <td><input type="text" name="scrollHeight" id="scrollHeight" /></td> </tr> <tr> <td align="right">scrollWidth（内容实际宽度）：</td> <td> </td> <td><input type="text" name="scrollWidth" id="scrollWidth" /></td> </tr> <tr> <td align="right">clientWidth（可见区域宽）：</td> <td> </td> <td><input type="text" name="clientWidth" id="clientWidth" /></td> </tr> <tr> <td align="right">clientHeight（可见区域高）：</td> <td> </td> <td><input type="text" name="clientHeight" id="clientHeight" /></td> </tr> <tr> <td align="right">offsetWidth（加滚动条宽？）：</td> <td> </td> <td><input type="text" name="offsetWidth" id="offsetWidth" /></td> </tr> <tr> <td align="right">offsetHeight（加滚动条高？）：</td> <td> </td> <td><input type="text" name="offsetHeight" id="offsetHeight" /></td> </tr> <tr> <td align="right">screenTop：</td> <td> </td> <td><input type="text" name="screenTop" id="screenTop" /></td> </tr> <tr> <td align="right">screenBottom：</td> <td> </td> <td><input type="text" name="screenBottom" id="screenBottom" /></td> </tr> <tr> <td align="right">screenLeft：</td> <td> </td> <td><input type="text" name="screenLeft" id="screenLeft" /></td> </tr> <tr> <td align="right">sheight（分辨率高）：</td> <td> </td> <td><input type="text" name="sheight" id="sheight" /></td> </tr> <tr> <td align="right">swidth（分分辨率宽）：</td> <td> </td> <td><input type="text" name="swidth" id="swidth" /></td> </tr> <tr> <td align="right">availHeight：</td> <td> </td> <td><input type="text" name="availHeight" id="availHeight" /></td> </tr> <tr> <td align="right">availWidth：</td> <td> </td> <td><input type="text" name="availWidth" id="availWidth" /></td> </tr> </table> <a href="javascript:a()" style="height:20px;display:block;">内容高度是400PX，点击查看所有属性值</a> </center> </div> </body> </html>

其实，我们可以用document.documentElement代替document.body来获取我们想要的结果将代码中的document.body替换为document.documentElement，再来看看各浏览器下的实际结果：
ii测试结果表明，IE系列浏览器对document.documentElement属性的解释是正确的，其它标准浏览器将offsetHeight解释成了scrollHeight。火狐和netscape更是把这两个属性调换了过来。不过总的来说各属性都可以有个相应的解释，不会像 document.body一样只有可怜的两种解释。
终于可以放心地使用JS方法获取各种页面高宽属性了吧^_^!
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原文地址：https://www.cnblogs.com/iclotus/p/1727545.html