I’ve been playing a bit with regular expressions lately and have to find some
useful tasks in order to practice the skill. So, today I wanted to make a little method
that strips HTML comments from an ASP.NET webpage at runtime. The practical use of
the exercise is somewhat limited for most developers, but some websites have so many
comments that it might just save a decent amount of bytes from the response stream.
The problem with this exercise is that a lot of JavaScript is using HTML comments
to hide it’s workings from older browsers. That would mean that those script tags
would be empty. That’s why I made a rule saying that every JavaScript has to implement
the HTML comments correctly. Some don’t so you have to change it your self.
This is how the JavaScript is wrongly commented which also breaks my regex.
<script type="text/javascript">
<!--
function Name()
{
}
-->
</script>
The commenting should look like this which is also the right way to do it.
<script type="text/javascript">
<!--//
function Name()
{
}
//-->
</script>
The regular expression is very simple and all you need to do is to add the following
method to your webpage, user control or master page.
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
private static Regex _Regex
= new Regex("((<!--
)((?!<!-- ).)*( -->))(\\r\\n)*", RegexOptions.Singleline);
protected override void Render(HtmlTextWriter writer)
{
using (StringWriter sw
= new StringWriter())
{
using (HtmlTextWriter htmlWriter
= new HtmlTextWriter(sw))
{
base.Render(htmlWriter);
writer.Write(_Regex.Replace(sw.ToString(), string.Empty));
}
}
}
Maybe not the most useful stuff I've ever written, but fine for learning. The only
thing that bugs me is the JavaScript rule.
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