treeview选中父节点自动选中子节点

所用的javascript代码：


<script type="text/javascript">
    function public_GetParentByTagName(element, tagName) 
     { 
        var parent = element.parentNode; 
        var upperTagName = tagName.toUpperCase(); 
        //如果这个元素还不是想要的tag就继续上溯 
        while (parent && (parent.tagName.toUpperCase() != upperTagName)) 
        { 
            parent = parent.parentNode ? parent.parentNode : parent.parentElement; 
        } 
        return parent; 
    }

    //设置节点的父节点Cheched――该节点可访问，则他的父节点也必能访问 
    function setParentChecked(objNode) 
    { 
        var objParentDiv = public_GetParentByTagName(objNode,"div"); 
        if(objParentDiv==null || objParentDiv == "undefined") 
        { 
            return; 
        } 
        var objID = objParentDiv.getAttribute("ID"); 
        objID = objID.substring(0,objID.indexOf("Nodes")); 
        objID = objID+"CheckBox"; 
        var objParentCheckBox = document.getElementById(objID); 
        if(objParentCheckBox==null || objParentCheckBox == "undefined") 
        {