网页html中鼠标光标位置所在dom节点

在HTML文本编辑器中如何获得光标父节点对象？

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>
    鼠标光标位置所在节点
</title>
 <script>
 var isIE = navigator.userAgent.indexOf("MSIE")>0;

var Q_EDITFORM_DOCUMENT = null;
var Q_SELECTION = null;
var Q_RANGE = null;
var Q_RANGE_TEXT = "";

function getParentNode()
{
        if(isIE)
        {
                return document.selection.createRange().parentElement();
        }
        else
        {                
                var startRangeNode = Q_RANGE.startContainer;
                if (startRangeNode.nodeType == 3) 
                {
                        var textNode = startRangeNode;
                        startRangeNode = textNode.parentNode;
                } 
                else 
                {
                        if (startRangeNode.tagName.toLowerCase() == 'html') 
                        {
                                startRangeNode = startRangeNode.childNodes[0].nextSibling;
                        } 
                }
                return startRangeNode;
        }
}

//插入div的相关处理函数
function QEditformDocument()
{
        if (isIE) 
        {
                Q_EDITFORM_DOCUMENT = document;
        } 
        else 
        {
                Q_EDITFORM_DOCUMENT = document;
        }
}

function QSelection()
{
        if (isIE) 
        {
                Q_SELECTION = Q_EDITFORM_DOCUMENT.selection;
                Q_RANGE = Q_SELECTION.createRange();
                Q_RANGE_TEXT = Q_RANGE.text;
                //alert(Q_RANGE_TEXT);
        } 
        else 
        {
                Q_SELECTION = Q_EDITFORM_DOCUMENT.getSelection();
        Q_RANGE = Q_SELECTION.getRangeAt(0);
                Q_RANGE_TEXT = Q_RANGE.toString();
                //console.dir(Q_RANGE_TEXT);
        }
}


        function test(){
            QEditformDocument();
            QSelection();
            var parentobj = getParentNode();
            console.dir(parentobj);
        }

 </script>

</head>
<body>
<div contenteditable="true" onclick="test();">
<b>点我，我是b节点</b><br/>
<i>点我，我是i节点</i><br/>
<em>点我，我是em节点</em>
</div>
</body>
</html>

2014-08-28

网页html中 鼠标光标位置所在dom节点