IE在DOM操作有表单控件时的bug

bug描述
当象下例中那样操作了表单radio/checkbox的DOM结构时（或者直接影响了他们的结构时）选中的checkbox/radio将会自动恢复到默认状态，有如点了reset按钮一样。

<！DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><html><head><title>Rank"s HTML document</title><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><meta http-equiv="Pragma" content="no-cache" /> <meta http-equiv="Cache-Control" content="no-cache" /> <meta http-equiv="Expires" content="0" /><meta http-equiv="ImageToolbar" content="no" /><meta http-equiv="Creator.name" content="Rank, BlueDestiny, never-online" /><style type="text/css" title="default" media="screen">/*<！[CDATA[*/body { font-size:80%; line-height:1.5; }body, button { font-family:arial; }button { padding:0 0.3em 0 0.3em; }h1, h3 { margin:0; padding:0; }h1 { font-size:2.3em; }h3 { font-size:1.3em; }form { display:inline-block; }div.link { padding:1em; }div.content { background:#ffc; padding:1em; border:1px solid #222; margin:1em 0 1em; }#rdoWrapper { }#hd { text-align:center; }/*]]>*/</style></head><body><h1> IE form control bug </h1>from: <em>never-online weblog</em><h3> 1. Select radio to checked </h3><form method="post"><input type="radio" name="rdo" id="rdo-1" value="rdo-1" checked><label for="rdo-1">radio1</label><input type="radio" name="rdo" id="rdo-2" value="rdo-2"><label for="rdo-2">radio2</label><input type="radio" name="rdo" id="rdo-3" value="rdo-3"><label for="rdo-3">radio3</label><input type="radio" name="rdo" id="rdo-4" value="rdo-4"><label for="rdo-4">radio4</label></form><h3> 2. Click button to change dom structure </h3><p class="p"><button type="button" onclick="handleChangeDom（）">test</button><br/><script type="text/javascript">//<！[CDATA[function getRadioValue（ctlName） {var ctls = document.getElementsByName（ctlName）;var len = ctls.length;for （var i=0; i<len; i++） {if （ctls[i].checked） {return ctls[i].value;}}}function handleChangeDom（） {alert（"before append, you select radio value is ""+getRadioValue（"rdo"）+"""）;var wrapper = document.getElementById（"rdoWrapper"）;document.body.appendChild（wrapper）;alert（"after append, you select radio value is ""+getRadioValue（"rdo"）+"""）;}//]]></script></body></html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]
解决方法
可以在操作DOM之前，用defaultChecked来设置checked的值。

<！DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><html><head><title>Rank"s HTML document</title><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><meta http-equiv="Pragma" content="no-cache" /> <meta http-equiv="Cache-Control" content="no-cache" /> <meta http-equiv="Expires" content="0" /><meta http-equiv="ImageToolbar" content="no" /><meta http-equiv="Creator.name" content="Rank, BlueDestiny, never-online" /><style type="text/css" title="default" media="screen">/*<！[CDATA[*/body { font-size:80%; line-height:1.5; }body, button { font-family:arial; }button { padding:0 0.3em 0 0.3em; }h1, h3 { margin:0; padding:0; }h1 { font-size:2.3em; }h3 { font-size:1.3em; }form { display:inline-block; }div.link { padding:1em; }div.content { background:#ffc; padding:1em; border:1px solid #222; margin:1em 0 1em; }#rdoWrapper { }#hd { text-align:center; }/*]]>*/</style></head><body><h1> fixed IE form control bug </h1>from: <em>never-online weblog</em><h3> 1. Select radio to checked </h3><form method="post"><input type="radio" name="rdo" id="rdo-1" value="rdo-1" checked><label for="rdo-1">radio1</label><input type="radio" name="rdo" id="rdo-2" value="rdo-2"><label for="rdo-2">radio2</label><input type="radio" name="rdo" id="rdo-3" value="rdo-3"><label for="rdo-3">radio3</label><input type="radio" name="rdo" id="rdo-4" value="rdo-4"><label for="rdo-4">radio4</label></form><h3> 2. Click button to change dom structure </h3><p class="p"><button type="button" onclick="handleChangeDom（）">test</button><br/><script type="text/javascript">//<！[CDATA[function getRadioValue（ctlName） {var ctls = document.getElementsByName（ctlName）;var len = ctls.length;for （var i=0; i<len; i++） {if （ctls[i].checked） {return ctls[i].value;}}}function setRadioDefaultValue（ctlName） {var ctls = document.getElementsByName（ctlName）;var len = ctls.length;for （var i=0; i<len; i++） {ctls[i].defaultChecked = ctls[i].checked;}}function handleChangeDom（） {alert（"before append, you select radio value is ""+getRadioValue（"rdo"）+"""）;setRadioDefaultValue（"rdo"）;var wrapper = document.getElementById（"rdoWrapper"）;document.body.appendChild（wrapper）;alert（"after append, you select radio value is ""+getRadioValue（"rdo"）+"""）;}//]]></script></body></html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]