HTML Code Killer

robindean · #1 05-20-2007, 08:05 PM

I'm hoping to devise a javascript that will remove an html comment. "Why" is not so much a concern as "how".

Another more experienced programmer presented some very interesting code that I'd like to build from.

The html comment I'm trying to remove is in the <head> of my page and reads:

Code:

<!-- </textarea> -->

In accordance with how toicontien's code appears to function, I've placed comment tags around the other comment, which now has it reading:

Code:

<!-- kill --><!-- </textarea> --><!-- kill -->

The function is as follows:

Code:

function KillCode() {
if (document.getElementsByTagName) {
var head = document.getElementsByTagName('head')[0];
var headHTML = head.innerHTML;
var headHTMLPieces = headHTML.split('<!-- kill -->');
head.innerHTML = headHTMLPieces[0] + headHTMLPieces[2];
}
}

It's not working yet and I'm not sure why. Can I get some guidance? When/where should I call the function? Is there a better way to remove the html comment using javascript?

**Jeff Mott** · #2 05-21-2007, 01:08 AM

I can somewhat answer your question only because I know your past situation. If you use this code, for instance (I'm using base instead of META refresh only because it's more convenient while testing):

Code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
 "http://www.w3.org/TR/html4/strict.dtd">

<html lang="en-us">

<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">

<script type="text/javascript">document.write('<!-- <textarea rows="0" cols="0" style="width: 0px; height: 0px; display: none;">');</script>
<base href="http://www.w3.org/">
<!-- kill --><!-- </textarea> --><!-- kill -->
</head>

<body>
	<p>Hello, <a href="123">World!</a></p>
</body>

</html>

And now, with FF's DOM Inspector, you can see how the generated code ends up:

Code:

<html lang="en-us"><head><title></title>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">

<script type="text/javascript">document.write('<!-- <textarea rows="0" cols="0" style="width: 0px; height: 0px; display: none;">');</script><!-- <textarea rows="0" cols="0" style="width: 0px; height: 0px; display: none;">
<base href="http://www.w3.org/">
<!-- kill --><!--></head><body>--&gt;<!-- kill -->

	<p>Hello, <a href="123">World!</a></p>

</body></html>

Part of the problem, I'm sure, is that the HTML comment ends at the two dashes just before the first "kill." Everything after the first "kill" then becomes a convoluted syntax error. There is no defined way for the browser to deal with such wrong code, so the results are unpredictable.

robindean · #3 05-21-2007, 01:34 AM

I see, so we've got trouble as a result of the javascripts end result. The puzzle, once again, grows.

**Fang** · #4 05-21-2007, 02:13 AM

Code:

function removeComments() {
var head=document.getElementsByTagName('head')[0];
var children=head.childNodes;
for(var i=0; i<children.length; i++) {
    if(children[i].nodeType==8) {head.removeChild(children[i]);}
    }
}

If there are multiple comments in the head, you may need to loop through the nodes in reverse order as the node map is immediately updated after a node is removed.

robindean · #5 05-21-2007, 02:19 AM

Thanks Fang!

However, I managed to devise a solution to my alternate thread which involved a different outcome.

Regardless, this answer strongly applies others who might be interested in doing this.

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