Question

I have an HTML textarea element. I want to prevent a user from entering any HTML tags in this area. How do I detect if a user has entered any HTML a textarea with JavaScript?

Thank you

Answer 1

firstly, bear in mind that you’ll need to re-validate on the server side, since anyone can fake a http post, and if they have javascript disabled then of course you have no control 🙂

what i’d do is

<textarea onkeypress="disableHtml(this);" name="text"></textarea>

and for the javascript

function disableHtml(element) {
  element.value = element.value.replace(/[<>]/g, '');
}

another way to do this would be to replace < and > with &lt; and &gt; on the server side, which is the better way because it’s secure and people can still frown >:)

[edit : you can make the regexp as clever as you like, if you want to only detect certain tags for instance]