Is there a DOM API for querying comment nodes?

Question

I have a document with a debugging comment in it that looks like this:

Is there a way to query the DOM to a

Answer 1

The nodeType core property allows you to differentiate between types of nodes. In this particular case, 8 represents comments. As they have no selector, you'll need to loop through their parent to get them (which sucks, I know). The following code filters them out for you:

$("*").contents().filter(function(){
    return this.nodeType == Node.COMMENT_NODE;
})

And my own jQuery-less version, because some people don't have it:

function getAllComments() {
    var t = [],
        recurse = function (elem) {
            if (elem.nodeType == Node.COMMENT_NODE) {
                t.push(elem);
            };
            if (elem.childNodes && elem.childNodes.length) {
                for (var i = 0; i < elem.childNodes.length; i++) {
                    recurse(elem.childNodes[i]);
                };
            };
        };
    recurse(document.getElementsByTagName("html")[0]);
    return t;
};

If you'd like to search on a specific node, re-bind the document.getElementsByTagName call to a variable of your choosing.

Edit: fiddle to demonstrate the use, done by Jason Sperske!

Answer 2

There's the TreeWalker APIs:

var tw = document.createTreeWalker(document, NodeFilter.SHOW_COMMENT, null, null),
    comment;
while (comment = tw.nextNode()) {
    // ...
}

This isn't supported by IE8 and lower.

T.J. in the comments provided a link to the specs. I kind of always use just TreeWalkers, but in your case a NodeIterator is fine too.