[英]Generate an XML doc from the DOM while skipping over certain elements
我有尝试从中生成XML文档的HTML。 我想跳过某些元素(基本上是除div以外的所有元素),为此,我编写了一个简单的DOM遍历函数,但似乎陷入了无限循环。 (下面有更多详细信息。)
<div id="browserDiv">
<h3>Library</h3>
<ul>
<li>
<div id="t-0" class="section topic" data-content="2b-2t-38-w-2c-2w-2t-33-36-3d">
<p>Set Theory</p>
<img class="toggle"><img class="edit">
<img class="add-entry"><img class="delete">
<ul>
<li>
<div id="t-0-0" class="section topic" data-content="1t-3c-2x-33-31-37">
<p>Axioms</p>
<img class="toggle"><img class="edit">
<img class="add-entry"><img class="delete">
<ul>
<li>
<div id="t-0-0-0" class="section topic" data-content="1t-3c-2x-33-31-w-33-2u-w-2b-2t-34-2p-36-2p-38-2x-33-32">
<p>Axiom of Separation</p>
<img class="toggle"><img class="edit">
<img class="add-entry"><img class="delete">
<ul>
<li>
<img class="add-new">
</li>
</ul>
</li>
<li>
<img class="add-new">
</li>
</div>
</li>
<li>
<img class="add-new">
</li>
</ul>
</div>
</li>
<li>
<div id="t-1" class="section topic" data-content="1t-32-2p-30-3d-37-2x-37">
<p>Analysis</p>
<img class="toggle"><img class="edit">
<img class="add-entry"><img class="delete">
<ul>
<li>
<img class="add-new">
</li>
</ul>
</div>
</li>
<li>
<img class="add-new">
</li>
</ul>
</div>
而且我正在尝试将此html转换为XML文件。 但是XML只存储div
元素中包含的信息,因此在遍历DOM树时,我试图跳过所有其他元素。
<?xml version="1.0" encoding="UTF-8"?>
<library userid="095209376">
<title>UserID095209376's Library</title>
<topic children="yes" loadable="no">
<id>0</id>
<encoding>2b-2t-38-w-2c-2w-2t-33-36-3d</encoding>
<topic children="yes" loadable="no">
<id>0-0</id>
<encoding>1t-3c-2x-33-31-37</encoding>
<topic children="no" loadable="yes">
<id>0-0-0</id>
<encoding>1t-3c-2x-33-31-w-33-2u-w-2b-2t-34-2p-36-2p-38-2x-33-32</encoding>
</topic>
</topic>
<topic children="yes" loadable="no">
<id>1</id>
<encoding>1t-32-2p-30-3d-37-2x-37</encoding>
</topic>
</library>
(请注意,脚本标记仅用于使SO进行语法突出显示。)
<script>
function saveLibrary(){
var xmlDoc = document.implementation.createDocument('http://www.tuningcode.com', 'library');
var rootNode = document.getElementById('browserDiv');
console.log("rootNode here: " + rootNode);
var libraryTree = walkLibraryTree2(rootNode, xmlDoc);
xmlDoc.documentElement.appendChild(libraryTree);
var oSerializer = new XMLSerializer();
var sXML = oSerializer.serializeToString(xmlDoc);
console.log("xmlDoc: " + xmlDoc);
console.log(sXML);
}
function walkLibraryTree2(nodeToWalk, doc){
var elem = doc.createElement(nodeToWalk.tagName);
console.log(elem);
if(nodeToWalk.hasChildNodes()){
var ch = nodeToWalk.children;
for(var i = 0; i < ch.length; i++){
var theWalk = walkLibraryTree2(ch[i], doc);
if(theWalk != null){
if(ch[i].tagName == 'DIV'){
elem.appendChild(theWalk);
} else{
elem = theWalk;
}
}
}
return elem;
} else {
return null;
}
}
saveLibrary();
</script>
问题是,当我运行它时,(编辑)它花费的时间比应该花费的时间长得多,并且会生成如下内容:
<library xmlns="http://www.tuningcode.com"><LI xmlns=""/></library>.
换句话说,它不打印任何div,而仅打印一个li元素。 我已经将它打印到控制台了很多,即使只有上面显示的节点数量,它也可以将数千条语句打印到控制台。
如何跳过除div
元素之外的所有元素遍历树? 还是为什么上面的代码无法正常工作?
我认为您遇到了非常长的运行时间,因为对于for
循环的每次迭代walkLibraryTree2
两次调用walkLibraryTree2
,从而导致指数级扩展(您的HTML深度为13个级别,因此, walkLibraryTree2
被调用了8,000次以上)。
处理复杂的问题时,最好将其分解为较小的部分。 以下似乎有效:
<script>
function saveLibrary() {
var xmlDoc = document.implementation.createDocument(null, 'library');
var rootNode = document.getElementById('browserDiv');
console.log("rootNode here: " + rootNode);
appendNodes(xmlDoc.documentElement, processChildren(rootNode, xmlDoc));
var oSerializer = new XMLSerializer();
var sXML = oSerializer.serializeToString(xmlDoc);
console.log("xmlDoc: " + xmlDoc);
console.log(sXML);
}
// DomNode, Document -> Array[DomNode]
function processChildren(node, doc) {
var nodes = [],
i;
for (i = 0; i < node.childNodes.length; i += 1) {
nodes = nodes.concat(processNode(node.childNodes[i], doc));
}
return nodes;
}
// DomNode, Array[DomNode] -> void
function appendNodes(destNode, nodes) {
var i;
for (i = 0; i < nodes.length; i += 1) {
destNode.appendChild(nodes[i]);
}
}
// DomNode, Document -> Array[DomNode]
function processNode(node, doc) {
var children = processChildren(node, doc);
if (node.tagName == "DIV") {
return [createTopicElement(node, doc, children)];
} else {
return children;
}
}
// DomNode, Document, Array[DomNode] -> DomNode
function createTopicElement(baseNode, doc, children) {
var el = doc.createElement("topic"),
hasChildren = !! children.length,
id = node.id.substring(2),
encoding = node.getAttribute("data-content");
el.setAttribute("children", hasChildren ? "yes" : "no");
el.appendChild(createElementWithValue(doc, "id", id));
el.appendChild(createElementWithValue(doc, "encoding", encoding));
appendNodes(el, children);
return el;
}
// Document, String, String -> DomNode
function createElementWithValue(doc, name, value) {
var el = doc.createElement(name);
el.textContent = value;
return el;
}
saveLibrary();
</script>
生成XML:
<library>
<topic children="yes">
<id>0</id>
<encoding>2b-2t-38-w-2c-2w-2t-33-36-3d</encoding>
<topic children="yes">
<id>0-0</id>
<encoding>1t-3c-2x-33-31-37</encoding>
<topic children="no">
<id>0-0-0</id>
<encoding>1t-3c-2x-33-31-w-33-2u-w-2b-2t-34-2p-36-2p-38-2x-33-32</encoding>
</topic>
</topic>
</topic>
<topic children="no">
<id>1</id>
<encoding>1t-32-2p-30-3d-37-2x-37</encoding>
</topic>
</library>
我不知道您的loadable
属性是如何确定的,或者标题是从哪里来的,但这应该可以帮助您达到目标。
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