What language should I use to create a simple text-formatting application online?

I want to make a page for a website that will let the user create a blog post, and want them to be able to graphically edit the formatting, like paragraphs and styles, then convert this to html. Is there a way to do it in PHP? Do I need to use Javascript or Ajax or something?

From stackoverflow

• PHP (if you want dynamic behavior) with FCKeditor (on the client side) will do the job. Have a look at the demo. Another good editor is TinyMCE.

  lush : I took a brief look at both and TinyMCE's UI looks much more modern.

  cherouvim : I prefer FCKeditor which is more advanced though. I've used both. have a look at the trends: http://www.google.com/trends?q=fckeditor%2C+tinymce and a more elaborate comparison: http://webtecker.com/2008/04/02/fckeditor-vs-tinymce/

  sirconnorstack : A really simple and easy-to-use service is NicEdit (nicedit.com). It's hosted on their website, so all you have to do is add two lines of javascript.