Question

I am trying to add different styles within a textarea eg bold, different colors etc

WYSIWYG editors (eg tinyMCE) used in web pages typically do this but I am having trouble working out how they do it.

You cannot do this:

alt text http://www.yart.com.au/test/html.gif

So how do they achieve it?

Answer 1

Owen has the right idea. Those libraries replace the textarea with an iframe and then put the iframe’s document into designMode or contentEditable mode. This literally enables you edit the html document in the iframe while the browser then handles the cursor and all keystrokes for you and gives you an api that can be called to make styling changes (bold, italic, and so on). Then when the user submits the form they copy the innerHTML from the iframe into the original textarea. For more details about how to enable this mode and what you can do with it see: https://developer.mozilla.org/En/Rich-Text_Editing_in_Mozilla

However, my suggestion to you is to use one of the existing rich text control libraries if you would like this ability on your site. I have built one before and found that you will spend huge amounts of time dealing with browser inconsistencies in order to get something that works well. Beyond the differences in how you enable editing features, you will also want to normalize the html that is created. For example, IE creates <br> elements when the user presses enter and FF creates <p> tags. For style changes IE uses <b>, <i>, etc. while FF uses spans with style attributes.