我想知道是否有人可以提供帮助。我的页面中的 HTML div 包含一个树控件，该控件根据用户按下的按钮显示或隐藏。该按钮触发一个 Ajax 事件，该事件在服务器上设置一个变量以显示或隐藏树，以便保持状态。
但这就是问题所在；重新显示树时，展开/折叠分支的图标不存在。到目前为止，我无法弄清楚为什么会这样。
树如下所示：第一个图形显示了应有的树，第二个图形显示了隐藏并重新显示后的树。
替代文字 http://www.dcs.bbk.ac.uk/~martin/Tree_with_icons.png 替代文字 http://www.dcs.bbk.ac.uk/~martin/Tree_without_icons.png
树的 HTML 作为列表构建在服务器上，每个列表项都有一个对 CSS 的类引用，如下所示：
ul.tree li.liOpen .bullet {
background: url(myApp_Minus.png) center left no-repeat;
cursor: pointer;
}
ul.tree li.liClosed .bullet {
background: url(myApp_Plus.png) center left no-repeat;
cursor: pointer;
}
ul.tree li.liBullet .bullet {
background: url(myApp_Hyphen.png) center left no-repeat;
cursor: pointer;
}
任何人都可以建议在重新显示树时显示图标的方法吗？
我尝试在 div、内联 CSS 元素等中放置指向 CSS 文件的链接，但没有成功。
欢迎任何帮助。
我在运行时附上了树的 HTML 的摘录：
<td align = "left">
<div id = "tree"><ul class = "tree" id = "navTree">
<li class = "liOpen">
<a href = "/myDataSharer/aboutConcept#communities">
<img alt = "Community" src = "/myDataSharer/images/myDataSharer_Community_Small.png">
</a> 
<a href = "/myDataSharer/commDashboard?CommNo=1&TagText=">Martin</a>
<ul>
<li class = "liOpen">
<a href = "/myDataSharer/aboutConcept#datasets">
<img alt = "Tabular dataset" src = "/myDataSharer/images/myDataSharer_TabularDataset_Small.png">
</a> 
<a href = "/myDataSharer/displayDataset?DatasetNo=1&pageRowNo=0&TagText=">Planets</a>
</li>
<ul>
<li>
<a href = "/myDataSharer/aboutConcept#QAV">
<img alt = "Visualisation" src = "/myDataSharer/images/myDataSharer_Visualisation_Small.png">
</a> 
<a href = "/myDataSharer/displayQAV?QAVNo=109&TagText=">Test QAV</a>
</li>
<li>
<a href
树本身位于一个名为“tree”的 div 中，它从 Javascript 方法更新如下：
document.getElementById("tree").style.visibility = "visible";
document.getElementById("tree").innerHTML = str;
树的Javascript是：
/* WRITTEN BY: Martin O'Shea for myDataSharerAlpha.
*
* This program has been inherited verbatim from the original author's sample code as mentioned
* below. No changes have been made other than a rename of a variable on line 121 from 'mktree' to 'tree'.
* ===================================================================
* Author: Matt Kruse <matt@mattkruse.com>
* WWW: http://www.mattkruse.com/
*
* NOTICE: You may use this code for any purpose, commercial or
* private, without any further permission from the author. You may
* remove this notice from your final code if you wish, however it is
* appreciated by the author if at least my web site address is kept.
*
* You may *NOT* re-distribute this code in any way except through its
* use. That means, you can include it in your product, or your web
* site, or any other form where the code is actually being used. You
* may not put the plain javascript up on your site for download or
* include it in your javascript libraries for download.
* If you wish to share this code with others, please just point them
* to the URL instead.
* Please DO NOT link directly to my .js files from your site. Copy
* the files to your server and use them there. Thank you.
* =====================================================================
* HISTORY
* ------------------------------------------------------------------
* December 9, 2003: Added script to the Javascript Toolbox
* December 10, 2003: Added the preProcessTrees variable to allow user
* to turn off automatic conversion of UL's onLoad
* March 1, 2004: Changed it so if a <li> has a class already attached
* to it, that class won't be erased when initialized. This allows
* you to set the state of the tree when painting the page simply
* by setting some <li>'s class name as being "liOpen" (see example)
*
* This code is inspired by and extended from Stuart Langridge's aqlist code:
* http://www.kryogenix.org/code/browser/aqlists/
* Stuart Langridge, November 2002
* sil@kryogenix.org
* Inspired by Aaron's labels.js (http://youngpup.net/demos/labels/)
* and Dave Lindquist's menuDropDown.js (http://www.gazingus.org/dhtml/?id=109)
*/
// Automatically attach a listener to the window onload, to convert the trees
addEvent(window,"load",convertTrees);
// Utility function to add an event listener
function addEvent(o,e,f){
if (o.addEventListener){ o.addEventListener(e,f,true); return true; }
else if (o.attachEvent){ return o.attachEvent("on"+e,f); }
else { return false; }
}
// utility function to set a global variable if it is not already set
function setDefault(name,val) {
if (typeof(window[name])=="undefined" || window[name]==null) {
window[name]=val;
}
}
// Full expands a tree with a given ID
function expandTree(treeId) {
var ul = document.getElementById(treeId);
if (ul == null) { return false; }
expandCollapseList(ul,nodeOpenClass);
}
// Fully collapses a tree with a given ID
function collapseTree(treeId) {
var ul = document.getElementById(treeId);
if (ul == null) { return false; }
expandCollapseList(ul,nodeClosedClass);
}
// Expands enough nodes to expose an LI with a given ID
function expandToItem(treeId,itemId) {
var ul = document.getElementById(treeId);
if (ul == null) { return false; }
var ret = expandCollapseList(ul,nodeOpenClass,itemId);
if (ret) {
var o = document.getElementById(itemId);
if (o.scrollIntoView) {
o.scrollIntoView(false);
}
}
}
// Performs 3 functions:
// a) Expand all nodes
// b) Collapse all nodes
// c) Expand all nodes to reach a certain ID
function expandCollapseList(ul,cName,itemId) {
if (!ul.childNodes || ul.childNodes.length==0) { return false; }
// Iterate LIs
for (var itemi=0;itemi<ul.childNodes.length;itemi++) {
var item = ul.childNodes[itemi];
if (itemId!=null && item.id==itemId) { return true; }
if (item.nodeName == "LI") {
// Iterate things in this LI
var subLists = false;
for (var sitemi=0;sitemi<item.childNodes.length;sitemi++) {
var sitem = item.childNodes[sitemi];
if (sitem.nodeName=="UL") {
subLists = true;
var ret = expandCollapseList(sitem,cName,itemId);
if (itemId!=null && ret) {
item.className=cName;
return true;
}
}
}
if (subLists && itemId==null) {
item.className = cName;
}
}
}
}
// Search the document for UL elements with the correct CLASS name, then process them
function convertTrees() {
setDefault("treeClass","tree");
setDefault("nodeClosedClass","liClosed");
setDefault("nodeOpenClass","liOpen");
setDefault("nodeBulletClass","liBullet");
setDefault("nodeLinkClass","bullet");
setDefault("preProcessTrees",true);
if (preProcessTrees) {
if (!document.createElement) { return; } // Without createElement, we can't do anything
uls = document.getElementsByTagName("ul");
for (var uli=0;uli<uls.length;uli++) {
var ul=uls[uli];
if (ul.nodeName=="UL" && ul.className==treeClass) {
processList(ul);
}
}
}
}
// Process a UL tag and all its children, to convert to a tree
function processList(ul) {
if (!ul.childNodes || ul.childNodes.length==0) { return; }
// Iterate LIs
for (var itemi=0;itemi<ul.childNodes.length;itemi++) {
var item = ul.childNodes[itemi];
if (item.nodeName == "LI") {
// Iterate things in this LI
var subLists = false;
for (var sitemi=0;sitemi<item.childNodes.length;sitemi++) {
var sitem = item.childNodes[sitemi];
if (sitem.nodeName=="UL") {
subLists = true;
processList(sitem);
}
}
var s= document.createElement("SPAN");
var t= '\u00A0'; //
s.className = nodeLinkClass;
if (subLists) {
// This LI has UL's in it, so it's a +/- node
if (item.className==null || item.className=="") {
item.className = nodeClosedClass;
}
// If it's just text, make the text work as the link also
if (item.firstChild.nodeName=="#text") {
t = t+item.firstChild.nodeValue;
item.removeChild(item.firstChild);
}
s.onclick = function () {
this.parentNode.className = (this.parentNode.className==nodeOpenClass) ? nodeClosedClass : nodeOpenClass;
return false;
}
}
else {
// No sublists, so it's just a bullet node
item.className = nodeBulletClass;
s.onclick = function () { return false; }
}
s.appendChild(document.createTextNode(t));
item.insertBefore(s,item.firstChild);
}
}
}
谢谢。
网页的Ajax如下图所示：
<script language="Javascript">
function xmlhttpPost(strURL) {
var xmlHttpReq = false;
var self = this;
// Mozilla / Safari.
if (window.XMLHttpRequest) {
self.xmlHttpReq = new XMLHttpRequest();
}
// IE.
else if (window.ActiveXObject) {
self.xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
}
self.xmlHttpReq.open('POST', strURL, true);
self.xmlHttpReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
self.xmlHttpReq.onreadystatechange = function() {
if (self.xmlHttpReq.readyState == 4) {
updatePage(self.xmlHttpReq.responseText);
}
}
self.xmlHttpReq.send(getQueryStr());
}
function getQueryStr() {
queryStr = "action=toggleTree";
return queryStr;
}
function updatePage(str) {
if (str == "false") {
// Hide tree buttons and tree.
document.getElementById("tree").style.visibility = "hidden";
document.getElementById("expColTreeButtons").style.visibility = "hidden";
}
else {
// Show tree buttons.
document.getElementById("expColTreeButtons").style.visibility = "visible";
// Show tree.
document.getElementById("tree").style.visibility = "visible";
document.getElementById("tree").innerHTML = str;
}
}
function toggleTree() {
// Make call to server to toggle tree.
document.getElementById("tree").innerHTML = "<img src='/myDataSharer/images/myDataSharer_Wait.gif' alt='Growing tree' />"
xmlhttpPost("/myDataSharer/toggleTree");
}
上面的 Ajax 是从具有三个按钮的表单触发的。“显示/隐藏”按钮可以查看事物；另外两个按钮也包含在一个 div 中，但它们没问题。
<form>
<input class = "treeButton" type="submit" value="Show / hide" onClick = "toggleTree(); return false;">
<div id = "expColTreeButtons">
<input class = "treeButton" type="submit" value="Expand all" onClick = "expandTree('navTree'); return false;">
<br />
<input class = "treeButton" type="submit" value="Collapse all" onClick = "collapseTree('navTree'); return false;">
<br />
</div>
</form>