.NET Remove/Strip JavaScript and CSS code blocks from HTML page

The quick 'n' dirty method would be a regex like this:

var regex = new Regex(
   "(\\<script(.+?)\\</script\\>)|(\\<style(.+?)\\</style\\>)", 
   RegexOptions.Singleline | RegexOptions.IgnoreCase
);

string ouput = regex.Replace(input, "");

The better* (but possibly slower) option would be to use HtmlAgilityPack:

HtmlDocument doc = new HtmlDocument();
doc.LoadHtml(htmlInput);

var nodes = doc.DocumentNode.SelectNodes("//script|//style");

foreach (var node in nodes)
    node.ParentNode.RemoveChild(node);

string htmlOutput = doc.DocumentNode.OuterHtml;

*) For a discussion about why it's better, see this thread.

Use HTMLAgilityPack for better results

or try this function

public string RemoveScriptAndStyle(string HTML)
{
    string Pat = "<(script|style)\\b[^>]*?>.*?</\\1>";
    return Regex.Replace(HTML, Pat, "", RegexOptions.IgnoreCase | RegexOptions.Singleline);
}