asp.net 2.0 的 TreeView 控件功能虽说强大,但其客户端控制很逊色,本文将讲解 TreeView 的客户端实现原理,并实现两个个性化操作：
(1) 节点的全部打开和关闭；
Client Side Expand/Collapse All Nodes For ASP.NET 2.0 TreeView.
(2) 只打开一个节点(关闭其他兄弟节点)。
Just one expanded node in ASP.NET 2.0 TreeView (When a client expand one node all other will collaps)
用记事本打开页面源代码，可以找到一下两个脚本引用：
<script src="/WebUI/WebResource.axd?d=RAQeBcDUNuP9iuS8q3tNEw2&t=633300220640000000" type="text/javascript"></script><script src="/WebUI/WebResource.axd?d=JuTdJhq3NM8Jq_RhssAkEg2&t=633300220640000000" type="text/javascript"></script> 将"/WebUI/WebResource.axd?d=RAQeBcDUNuP9iuS8q3tNEw2&t=633300220640000000"拷到地址栏尾，下载脚本，并以 .js 命名，另一个同样操作。分析第二个脚本文件，可以看到TreeView的很多客户端函数，其中关键的一个 TreeView_ToggleNode 就是客户端点击时触发的事件。
要想做个性化的操作，就得从 TreeView_ToggleNode 事件下手。我们无法更改.net封装好的脚本，只有“重写”。所谓的重写就是在原来的函数之后添加一个同名函数（因为js对于同名函数只调用最后一个）。
TreeView_ToggleNode 的原函数：
function TreeView_ToggleNode(data, index, node, lineType, children) {
var img = node.childNodes[0]; var newExpandState;
try {
if (children.style.display == "none") { children.style.display = "block"; newExpandState = "e"; if ((typeof(img) != "undefined") && (img != null)) { if (lineType == "l") { img.src = data.images[15];
} else if (lineType == "t") { img.src = data.images[12]; } else if (lineType == "-") { img.src = data.images[18]; } else { img.src = data.images[5]; } img.alt = data.collapseToolTip.replace(/\{0\}/, TreeView_GetNodeText(node)); } } else { children.style.display = "none"; newExpandState = "c"; if ((typeof(img) != "undefined") && (img != null)) { if (lineType == "l") { img.src = data.images[14]; } else if (lineType == "t") { img.src = data.images[11]; } else if (lineType == "-") { img.src = data.images[17]; } else { img.src = data.images[4]; } img.alt = data.expandToolTip.replace(/\{0\}/, TreeView_GetNodeText(node)); } } } catch(e) {} data.expandState.value = data.expandState.value.substring(0, index) + newExpandState + data.expandState.value.slice(index + 1);
}1. 节点的全部打开和关闭(Client Side Expand/Collapse All Nodes)
<html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"> <title>LeftMenu_Tree</title></head><body bgcolor="#DDEDFD"> <form id="form1" runat="server"> <a href="javascript:TreeviewExpandCollapseAll('<%=TreeView1.ClientID%>', true)">Expand All</a> <a href="javascript:TreeviewExpandCollapseAll('<%=TreeView1.ClientID%>', false)"> Collapse All</a> <asp:TreeView ID="TreeView1" SkinID="tvClass" runat="server" ShowLines="true" NodeWrap="false"> </asp:TreeView> </form></body></html><script language="javascript">//-----------------------------------------------------------------------------function $(s){return document.getElementById(s);}function isNull(_sVal){return (_sVal == "" || _sVal == null || _sVal == "undefined");}function TreeviewExpandCollapseAll(treeViewId, expandAll){ var displayState = (expandAll == true ? "none" : "block"); var treeView = $(treeViewId); if(treeView) { var treeLinks = treeView.getElementsByTagName("a"); var nodeCount = treeLinks.length; var flag = true; for(i=0;i<nodeCount;i++) { if(treeLinks[i].firstChild.tagName) { if(treeLinks[i].firstChild.tagName.toLowerCase() == "img") { var node = treeLinks[i]; var level = parseInt(node.id.substr(node.id.length - 1),10); var childContainer = GetParentByTagName("table", node).nextSibling; if(!isNull(childContainer)) { if(flag) { if(childContainer.style.display == displayState) { TreeView_ToggleNode(eval(treeViewId +"_Data"),level,node,'r',childContainer); } flag = false; } else { if(childContainer.style.display == displayState) { TreeView_ToggleNode(eval(treeViewId +"_Data"),level,node,'l',childContainer); } } } } } }//for loop ends }}function GetParentByTagName(parentTagName, childElementObj){ var parent = childElementObj.parentNode; while(parent.tagName.toLowerCase() != parentTagName.toLowerCase()) { parent = parent.parentNode; } return parent;}//-----------------------------------------------------------------------------</script><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"> <title>LeftMenu_Tree</title></head><body bgcolor="#DDEDFD"> <form id="form1" runat="server"> <a href="javascript:TreeviewExpandCollapseAll('<%=TreeView1.ClientID%>', true)">Expand All</a> , <a href="javascript:TreeviewExpandCollapseAll('<%=TreeView1.ClientID%>', false)"> Collapse All</a> <asp:TreeView ID="TreeView1" SkinID="tvClass" runat="server" ShowLines="true" NodeWrap="false"> </asp:TreeView> </form></body></html><script language="javascript">//2. 只打开一个节点,关闭其他兄弟节点(Just one expanded node, all other will collaps)function TreeView_ToggleNode(data, index, node, lineType, children) { var img = node.childNodes[0]; var newExpandState; try { //***折叠兄弟节点(Collapse Brothers)----- CollapseBrothers(data,children); //--------------------------------------- if (children.style.display == "none") { children.style.display = "block"; newExpandState = "e"; if ((typeof(img) != "undefined") && (img != null)) { if (lineType == "l") { img.src = data.images[15]; } else if (lineType == "t") { img.src = data.images[12]; } else if (lineType == "-") { img.src = data.images[18]; } else { img.src = data.images[5]; } img.alt = data.collapseToolTip.replace(/\{0\}/, TreeView_GetNodeText(node)); } } else { children.style.display = "none"; newExpandState = "c"; if ((typeof(img) != "undefined") && (img != null)) { if (lineType == "l") { img.src = data.images[14]; } else if (lineType == "t") { img.src = data.images[11]; } else if (lineType == "-") { img.src = data.images[17]; } else { img.src = data.images[4]; } img.alt = data.expandToolTip.replace(/\{0\}/, TreeView_GetNodeText(node)); } } } catch(e) {} data.expandState.value = data.expandState.value.substring(0, index) + newExpandState + data.expandState.value.slice(index + 1);}//折叠兄弟节点(Collapse Brothers)function CollapseBrothers(data,childContainer){ var parent = childContainer.parentNode; for(i=0; i< parent.childNodes.length; i++) { if(parent.childNodes[i].tagName.toLowerCase() =="div") { if(parent.childNodes[i].id != childContainer.id) { parent.childNodes[i].style.display = "none" } } else if(parent.childNodes[i].tagName.toLowerCase() =="table") { var treeLinks = parent.childNodes[i].getElementsByTagName("a"); if(treeLinks.length > 2) { var j=0; if(treeLinks[j].firstChild.tagName) { if(treeLinks[j].firstChild.tagName.toLowerCase() == "img") { var img = treeLinks[j].firstChild; if(i==0) img.src = data.images[8]; else if(i==parent.childNodes.length-2) img.src = data.images[14]; else img.src = data.images[11]; } } } } }}//-----------------------------------------------------------------------------</script>