我们在设计网页统一格式,希望尽可能减少重复性的代码.
比如Table中行的OnMouseOver与OnMouseOut效果,虽然我们可以用同一CSS去定义它们的效果,但是你必须在每个TR标签里加上
<tr OnMouseOver="..." OnMouseOut="...">
以前在网上找到一个简介CSS代码可以代替此效果 :
tr:hover{background-color:#DEF}
但是它不能在IE上运行,后来在网上搜索终于找到了我想要的东东hover.htc
把下面两段代码分别复制出来运行即可看到效果。

<html>
<head>
<title></title>
<style type="text/css">
.tb{width:666px;border-collapse:collapse;border:1px solid #EEE;font-size:14px;}
.tb th{background:#EEE;border-bottom:1px solid #CCC;padding:4px;}
.tb td{border:1px solid #EEE;padding:4px;}
.tb tr:hover{background-color:#DEF}
body{behavior:url(hover.htc);}
</style>
</head>
<body>
<table class="tb">
<tr>
<th>書本名称</th>
<th>单价</th>
<th>数量</th>
</tr>
<tr>
<td>《Java2大全》</td>
<td>100</td>
<td>43</td>
</tr>
<tr>
<td>《Code2大全》</td>
<td>199</td>
<td>54</td>
</tr>
<tr>
<td>《取經之路》</td>
<td>10</td>
<td>65</td>
</tr>
</table>
</body>
</html>
hover.htc:

<attach event="ondocumentready" handler="parseStylesheets" />
<script>
/**
* Whatever:hover - V1.42.060206 - hover & active
* ------------------------------------------------------------
* (c) 2005 - Peter Nederlof
* Peterned - http://www.xs4all.nl/~peterned/
* License - http://creativecommons.org/licenses/LGPL/2.1/
*
* Whatever:hover is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Whatever:hover is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* Credits and thanks to:
* Arnoud Berendsen, Martin Reurings, Robert Hanson
*
* howto: body { behavior:url("csshover.htc"); }
* ------------------------------------------------------------
*/
var csshoverReg = /(^|\s)(([^a]([^ ]+)?)|(a([^#.][^ ]+)+)):(hover|active)/i,
currentSheet, doc = window.document, hoverEvents = [], activators = {
onhover:{on:'onmouseover', off:'onmouseout'},
onactive:{on:'onmousedown', off:'onmouseup'}
}
function parseStylesheets() {
if(!/MSIE (5|6)/.test(navigator.userAgent)) return;
window.attachEvent('onunload', unhookHoverEvents);
var sheets = doc.styleSheets, l = sheets.length;
for(var i=0; i<l; i++)
parseStylesheet(sheets[i]);
}
function parseStylesheet(sheet) {
if(sheet.imports) {
try {
var imports = sheet.imports, l = imports.length;
for(var i=0; i<l; i++) parseStylesheet(sheet.imports[i]);
} catch(securityException){}
}
try {
var rules = (currentSheet = sheet).rules, l = rules.length;
for(var j=0; j<l; j++) parseCSSRule(rules[j]);
} catch(securityException){}
}
function parseCSSRule(rule) {
var select = rule.selectorText, style = rule.style.cssText;
if(!csshoverReg.test(select) || !style) return;
var pseudo = select.replace(/[^:]+:([a-z-]+).*/i, 'on$1');
var newSelect = select.replace(/(\.([a-z0-9_-]+):[a-z]+)|(:[a-z]+)/gi, '.$2' + pseudo);
var className = (/\.([a-z0-9_-]*on(hover|active))/i).exec(newSelect)[1];
var affected = select.replace(/:(hover|active).*$/, '');
var elements = getElementsBySelect(affected);
if(elements.length == 0) return;
currentSheet.addRule(newSelect, style);
for(var i=0; i<elements.length; i++)
new HoverElement(elements[i], className, activators[pseudo]);
}
function HoverElement(node, className, events) {
if(!node.hovers) node.hovers = {};
if(node.hovers[className]) return;
node.hovers[className] = true;
hookHoverEvent(node, events.on, function() { node.className += ' ' + className; });
hookHoverEvent(node, events.off, function() { node.className = node.className.replace(new RegExp('\\s+'+className, 'g'),''); });
}
function hookHoverEvent(node, type, handler) {
node.attachEvent(type, handler);
hoverEvents[hoverEvents.length] = {
node:node, type:type, handler:handler
};
}
function unhookHoverEvents() {
for(var e,i=0; i<hoverEvents.length; i++) {
e = hoverEvents[i];
e.node.detachEvent(e.type, e.handler);
}
}
function getElementsBySelect(rule) {
var parts, nodes = [doc];
parts = rule.split(' ');
for(var i=0; i<parts.length; i++) {
nodes = getSelectedNodes(parts[i], nodes);
} return nodes;
}
function getSelectedNodes(select, elements) {
var result, node, nodes = [];
var identify = (/\#([a-z0-9_-]+)/i).exec(select);
if(identify) {
var element = doc.getElementById(identify[1]);
return element? [element]:nodes;
}
var classname = (/\.([a-z0-9_-]+)/i).exec(select);
var tagName = select.replace(/(\.|\#|\:)[a-z0-9_-]+/i, '');
var classReg = classname? new RegExp('\\b' + classname[1] + '\\b'):false;
for(var i=0; i<elements.length; i++) {
result = tagName? elements[i].all.tags(tagName):elements[i].all;
for(var j=0; j<result.length; j++) {
node = result[j];
if(classReg && !classReg.test(node.className)) continue;
nodes[nodes.length] = node;
}
}
return nodes;
}
</script>