Find selected Part of the contents of textfield and modify it.

Hi,
I would like to build a script that can find out which part of the contents of a textfield was selected by a user and put html-strings in front and behind that selection onclick of a button.

For example:
The user enters a text into the textfield. He then selects a part of this text and clicks on a button and the javascript puts a <b> tag in front of the selected string and a </b> tag behind it.

I don't know whether this is at all possible or how simple that is. Sorry if this is very basic.

Thank you for any help.

Regards,
Ute

If you search the Post a JavaScript forum, you should be able to find something in there. These types of scripts are not very browser friendly.