建議用document.documentElement代替document.body
IE6在頁面內容超出窗口大小時將寬度屬性scrollWidth、clientWidth、offsetWidth都解釋爲內容實際寬度。
上次的測試說明了document.body屬性並不會給我們返回預期的結果,比如我們用document.body.clientHeight原本想取得“頁面可見區域高度”,可實際上返回的是“頁面實際內容高度”。
那我們怎麼辦呢?難道加上了文檔DTD類型之後就再也不能取到“可見區域高度”和“內容實際寬度”等等屬性了嗎?
在設計頁面時可能經常會用到固定層的位置,這就需要獲取一些html對象的座標以更靈活的設置目標層的座標,這裏可能就會用到document.body.scrollTop等屬性,但是此屬性在xhtml標準網頁或者更簡單的說是帶<!DOCTYPE ..>標籤的頁面裏得到的結果是0,如果不要此標籤則一切正常,那麼在xhtml頁面怎麼獲得body的座標呢,當然有辦法-使用document.documentElement來取代document.body,可以這樣寫
例:
var top = document.documentElement.scrollTop || document.body.scrollTop;
在javascript裏||是個好東西,除了能用在if等條件判斷裏,還能用在變量賦值上。那麼上例等同於下例。
例:
var top = document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop;
這麼寫可以得到很好的兼容性。
相反,如果不做聲明的話,document.documentElement.scrollTop反而會顯示爲0。
<!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="width: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(滾動條捲過的高):</td>
<td width="10"> </td>
<td width="209"><input type="text" name="scrollTop" id="scrollTop" /></td>
</tr>
<tr>
<td align="right">scrollLeft(滾動條捲過的寬):</td>
<td> </td>
<td><input type="text" name="scrollLeft" id="scrollLeft" /></td>
</tr>
<tr>
<td align="right">scrollHeight(內容實際高度):</td>
<td> </td>
<td><input type="text" name="scrollHeight" id="scrollHeight" /></td>
</tr>
<tr>
<td align="right">scrollWidth(內容實際寬度):</td>
<td> </td>
<td><input type="text" name="scrollWidth" id="scrollWidth" /></td>
</tr>
<tr>
<td align="right">clientWidth(可見區域寬):</td>
<td> </td>
<td><input type="text" name="clientWidth" id="clientWidth" /></td>
</tr>
<tr>
<td align="right">clientHeight(可見區域高):</td>
<td> </td>
<td><input type="text" name="clientHeight" id="clientHeight" /></td>
</tr>
<tr>
<td align="right">offsetWidth(加滾動條寬?):</td>
<td> </td>
<td><input type="text" name="offsetWidth" id="offsetWidth" /></td>
</tr>
<tr>
<td align="right">offsetHeight(加滾動條高?):</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(分分辨率寬):</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;">內容高度是400PX,點擊查看所有屬性值</a>
</center>
</div>
</body>
</html>