[英]How do I get an HTML comment with javascript
如果我有那個
<!-- some comment -->
如何獲取此元素並使用 javascript 更改內容? 如果我有一個代碼,我想刪除評論標簽,我該怎么做?
最好的方法是使用專用的NodeIterator實例迭代包含在給定根元素中的所有注釋。
function filterNone() {
return NodeFilter.FILTER_ACCEPT;
}
function getAllComments(rootElem) {
var comments = [];
// Fourth argument, which is actually obsolete according to the DOM4 standard, is required in IE 11
var iterator = document.createNodeIterator(rootElem, NodeFilter.SHOW_COMMENT, filterNone, false);
var curNode;
while (curNode = iterator.nextNode()) {
comments.push(curNode.nodeValue);
}
return comments;
}
window.addEventListener("load", function() {
console.log(getAllComments(document.body));
});
如果必須支持舊版瀏覽器(例如 IE <9),則需要自己遍歷 DOM 並提取節點類型為Node.COMMENT_NODE
元素。
// Thanks to Yoshi for the hint!
// Polyfill for IE < 9
if (!Node) {
var Node = {};
}
if (!Node.COMMENT_NODE) {
// numeric value according to the DOM spec
Node.COMMENT_NODE = 8;
}
function getComments(elem) {
var children = elem.childNodes;
var comments = [];
for (var i=0, len=children.length; i<len; i++) {
if (children[i].nodeType == Node.COMMENT_NODE) {
comments.push(children[i]);
}
}
return comments;
}
無論您從上面選擇哪種方式,您都會收到相同的節點 DOM 對象。
訪問評論的內容就像commentObject.nodeValue
一樣簡單。
刪除評論有點冗長: commentObject.parentNode.removeChild(commentObject)
你必須遍歷 DOM 才能得到它。 評論DOM元素的nodeType
為8
if( oNode.nodeType === 8 ) {
oNode.parentNode.removeChild( oNode );
}
將是一種方法
這是一個檢索評論的 JQuery 插件:
基本思想是查看nodes
,而不是elements
:
http://www.w3schools.com/htmldom/dom_nodes.asp
您從document
對象開始,並使用childNodes
集合遍歷它們。 您必須檢查node.nodeType == 8
它將只返回注釋節點(請注意,您需要遞歸遍歷子節點)。
我需要為整個網頁存儲一個模板。 但是 <template>-tag 不能包含例如 <html>-tag。 所以我決定將我的模板存儲在 HTML 注釋中。
我將 HTML 注釋放在隱藏的 <div> 中,以便更輕松地檢索該特定 HTML 注釋中的文本,而不必費心將其與其他 HTML 注釋區分開來。
這是一個演示,說明如何使用 createTreeWalker 檢索 HTML 注釋中的內容。
alert( document.createTreeWalker( document.getElementById('commentDiv'), NodeFilter.SHOW_COMMENT, null, false ).nextNode().nodeValue );
<p>Getting the text in a HTML-comment.</p> <p>I use createTreeWalker to make sure we don't simply capture an empty text node by mistake. You could make the code even simpler, but then you must make sure that the <div>-tag is immediately followed by the "<!--", like this "<div><!--". But if that breaks because of for example autoformating in an editor, so that you get a line feed in between or so, then the simpler method will fail. That is why I prefere to use the createTreeWalker here.</p> <!-- This is NOT the comment we want to get text from --> <div id="commentDiv" style="display:none;"> <!-- This is THE text, and you can have anything in here <> <div> <script>alert('hello');</script> etc. except of course an end of HTML-comment. An advantage of this way to store a template compared to using the <template>-tag, is that the <template>-tag can for example not contain a <html>-tag, in case you need to have a template for an entire web page. Check also my explanation down in the body text for why I use createTreeWalker instead of some simpler code. --> </div> <!-- This is also NOT the comment we want to get text from --> <p>End of body.</p>
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