Detect HTML in ASP.NET
<p>(clarification: this is an old question that has been tweaked for admin purposes)</p>

<p>There have been a fair amount of questions on this site about parsing HTML from textareas and whatnot, or not allowing HTML in Textboxes.  My question is similar: How would I detect if HTML is present in the textbox?  Would I need to run it through a regular expression of all known HTML tags? Is there a current library for .NET that has the ability to detect when HTML is inserted into a Textarea?</p>

<p>Edit: Similarly, is there a JavaScript Library that does this?</p>

<p>Edit #2: Due to the way that the web app works (It validates textarea text on asyncronous postback using the Validate method of ASP.NET), it bombs before it can get back to the code-behind to use HTML.Encode.  My concern was trying to find another way of handling HTML in those instances.</p>
